JPH11349860A - Polyester resin for powder coating material and powder coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin for a powder coating material which can form a coating film excellent in long-term weatherability and in mechanical properties and to provide a powder coating material contg. the same. SOLUTION: This polyester resin is formed from an acid component mainly comprising isophthalic acid and an alcohol component comprising 15-99.5 mol.% neopentyl glycol and/or ethylene glycol and 0.5-85 mol.% diol having a mol.wt. of 200 or higher and has a hydroxy value of 10-80 mgKOH/g, a number average mol.wt. of 2,500-8,000, a softening point of 100-135 deg.C, and a glass transition temperature of 35-75 deg.C. The powder coating material is prepd. by compounding the polyester resin with an isocyanate curative and other conventional ingredients for coating materials.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyester resin for powder coatings and a powder coating containing the polyester resin. More specifically, the present invention relates to a polyester resin for powder coating and a powder coating capable of forming a coating film having excellent long-term weather resistance and excellent mechanical properties.

[0002]

2. Description of the Related Art In recent years, as concerns about the global environment are increasing in society, consideration of environmental issues has become one of the important issues in the field of paints. Under such circumstances, the amount of the powder coating not using an organic solvent tends to increase year by year because the volatile component in the coating is equal to zero and the air does not pollute the air.

Conventionally, powder coatings have been mainly used for indoor products such as steel furniture and microwave ovens. However, as the amount of powder coating has been increased, the range of applications has been expanded. Recently, powder coatings have been used for outdoor products such as vending machines. The application of has become strongly required.

At present, an acrylic resin-based powder coating is known as a powder coating having long-term weather resistance applicable to outdoor products. However, this resin is expensive and has poor compatibility with other powder coatings, and even a small amount of mixed resin can cause cissing on the coating surface of other powder coatings. There is a drawback that you can not.
On the other hand, polyester resin-based powder coatings are inexpensive and do not cause repelling, but have poor long-term weather resistance and are not suitable for outdoor use.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a powder capable of forming a coating film having excellent long-term weather resistance applicable to outdoor products and excellent mechanical properties. An object of the present invention is to provide a polyester resin for body coating and a powder coating containing the polyester resin.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a polyester resin having a hydroxyl value is used, and the main acid component constituting the polyester resin is isophthalic acid. In addition, by blending an isocyanate-based curing agent as a curing agent with a polyester resin in which the alcohol component is neopentyl glycol and / or ethylene glycol and a diol unit having a molecular weight of 200 or more, not only long-term weather resistance but also mechanical properties are obtained. The inventors have found that an excellent powder coating can be obtained, and have reached the present invention.

[0007] The polyester resin for powder coating and the powder coating of the present invention were used in a sunshine carbon arc lamp type accelerated weathering test shown in JlSK5400 to obtain a 15%.
It retains a gloss retention of 80% or more even after the test of 00 hours, and is sufficiently suitable for outdoor use.

[0008] Regarding mechanical properties, JlSK5
In the Erichsen value test (break distance method) shown in 400, the conventional polyester resin whose acid component is mainly composed of terephthalic acid is generally known to reach a value of approximately 8 to 10 mm, Considering practical performance in practice, it is sufficient that the value is 5 mm or more. In that sense, the polyester resin for powder coating and the powder coating of the present invention are sufficiently suitable for practical use.

Incidentally, polyester resins and powder coatings for powder coatings having improved weather resistance are disclosed in
Although it is described in Japanese Patent No. 284974, this is a powder coating of a type obtained by mixing a polyepoxy compound as a curing agent with a polyester resin having a predetermined acid value, and the polyester resin for powder coating of the present invention. And powder coatings.

On the other hand, the present inventors have made a polyester resin for powder coating and a powder coating having improved weather resistance which are mainly composed of isophthalic acid and 2-methyl-1,3-propanediol and have a hydroxyl value of Japanese Patent Application Laid-Open No. 7-70475 proposes a polyester resin having an isocyanate-based curing agent as a curing agent.

However, the powder coating described in JP-A-7-70475 has an excellent balance between weather resistance and mechanical properties, but has a high gloss retention in an accelerated weather resistance test.
It became 50% after approximately 1500 hours, and it was difficult to apply to applications requiring higher weather resistance.

The gist of the present invention is as follows. 1. The acid component is mainly composed of isophthalic acid, and the alcohol component is composed of 15 to 99.5 mol% of neopentyl glycol and / or ethylene glycol and 0.5 to 85 mol% of a diol unit having a molecular weight of 200 or more. 80 mgKOH / g, number average molecular weight 2500
Polyester resin for powder coatings having a softening point of 100 to 135 ° C and a glass transition point of 35 to 75 ° C. 2. 2. The polyester resin according to item 1, wherein the diol unit having a molecular weight of 200 or more constituting the polyester resin is 2,2-dimethyl-3.
Polyester resin for powder coatings which is -hydroxypropyl-2,2-dimethyl-3-hydroxypropionate and / or dimer diol having 36 carbon atoms and / or hydrogenated bisphenol A. 3. 3. A powder coating obtained by mixing an isocyanate-based curing agent and various coating materials with the polyester resin for powder coating according to 1 or 2 above.

Hereinafter, the configuration of the present invention will be described in detail. In the polyester resin of the present invention, the acid component is mainly composed of isophthalic acid, and the ratio of the isophthalic acid is preferably 70 to 100 mol% in the acid component. If the content of isophthalic acid is less than 70 mol%, sufficient weather resistance cannot be obtained. Terephthalic acid can be exemplified as an optimal acid component that can be used in combination with isophthalic acid without impairing the effects of the present invention. However, if the proportion of terephthalic acid is 30
If it exceeds mol%, the weather resistance will decrease.

In addition to terephthalic acid, acid components that can be used in combination with isophthalic acid within a range that does not impair the effects of the present invention include phthalic anhydride, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, 5-tert-butyl-1,3- Examples thereof include benzenedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and hydrogenated dimer acid. Further, a tri- or tetra-functional acid component such as trimellitic anhydride, trimesic acid, and pyromellitic anhydride may be used in combination as long as the polyester resin is not gelled.

In the polyester resin of the present invention, the alcohol component is mainly composed of neopentyl glycol and / or ethylene glycol and a diol unit having a molecular weight of 200 or more, and the proportion of neopentyl glycol and / or ethylene glycol in the alcohol component is Fifteen
９９99.5 mol%, and the proportion of diol units having a molecular weight of 200 or more is 0.5 to 85 in the alcohol component.
Preferably it is mol%.

In the polyester resin of the present invention, when ethylene glycol is used in the alcohol component, it is limited to the case where the proportion of isophthalic acid in the acid component is 90 mol% or more. When the proportion of isophthalic acid is less than 90 mol%, the use of ethylene glycol lowers the weather resistance.

The polyester resin of the present invention is completed when the proportion of neopentyl glycol and / or ethylene glycol is less than 15 mol% in the alcohol component, in other words, when the proportion of diol units having a molecular weight of 200 or more exceeds 85 mol%. The softening point and the glass transition point of the polyester resin are lowered, and when it is used as a powder coating, particles are fused and solidified, that is, so-called blocking tends to occur. Also, the weather resistance is reduced. On the other hand, when the content of the diol unit having a molecular weight of 200 or more is less than 0.5 mol%, in other words, neopentyl glycol and / or
Alternatively, if the amount of ethylene glycol exceeds 99.5 mol%, the mechanical properties decrease.

In the polyester resin of the present invention, the diol unit having a molecular weight of 200 or more used together with neopentyl glycol and / or ethylene glycol must have a molecular weight of 200 or more. If the molecular weight is less than 200, sufficient mechanical properties cannot be obtained. Although the upper limit cannot be clearly defined, if the molecular weight of the diol unit is too large, blocking tends to occur because the softening point or glass transition point of the polyester resin is lowered, so that a diol unit having a molecular weight of 600 or less is used. Is preferred.

The diol unit having a molecular weight of 200 or more includes 2,2-dimethyl-3-hydroxypropyl-2,
Most preferably, 2-dimethyl-3-hydroxypropionate (molecular weight 204) and / or dimer diol having 36 carbon atoms (molecular weight 536) is used. As an example of a dimer diol having 36 carbon atoms, a carboxyl group at the molecular terminal of a high-purity dimer acid containing 98% or more of a dimer (unsaturated fatty acid) having 18 carbon atoms derived from vegetable oil is converted to a methyl ester. After the conversion, a compound which is hydrogenated and reduced at a high temperature and a high pressure to form a hydroxyl group is exemplified. As other diol units having a molecular weight of 200 or more, hydrogenated bisphenol A (molecular weight 240) can be exemplified.

Here, the above-mentioned various diol units having a molecular weight of 200 or more are commercially available from several manufacturers.
-Dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate is "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, Ltd., and 36-carbon dimer diol is "Pespol HP-1" manufactured by Toagosei Co., Ltd.
000 "(this compound has four alkyl chains of 6 to 8 carbon atoms in an X-shape with a cyclohexane ring as a branch point, of which two terminals are methyl groups and the other two terminals are methyl groups. And a hydrogenated bisphenol A, "Rikabinol HB" manufactured by Nippon Rika Co., Ltd., which can be used in combination.

In the present invention, it has been described above that the proportion of the diol unit having a molecular weight of 200 or more constituting the polyester resin is preferably 0.5 to 85 mol% in the alcohol component. It is necessary to use the ratio appropriately according to the molecular weight of the compound.

That is, in the case of a diol unit having a molecular weight of about 200 to 300, for example, 2,2-dimethyl-
In the case of 3-hydroxypropyl-2,21-dimethyl-3-hydroxypropionate or hydrogenated bisphenol A, the optimum ratio is 3 to 85 mol%, and the molecular weight is generally about 400 to 600. In this case, for example, in the case of a dimer diol having 36 carbon atoms, the optimum ratio is 0.5 to 5 mol%. By this optimization, the weather resistance and mechanical properties of the polyester resin for powder coating and the powder coating of the present invention become practically sufficient.

As long as the effects of the present invention are not impaired, neopentyl glycol and / or ethylene glycol,
Examples of the alcohol component that can be used in combination with the diol unit having a molecular weight of 200 or more include diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol,
1,3-butanediol, 1,4-butanediol, 2
-Methyl-1,5-pentanediol, 1,6-hexanediol, 3,3-dimethylolheptane, 1,4-
Examples thereof include cyclohexane dimethanol and bisphenol A ethylene oxide adduct.

Further, a tri- or tetrafunctional alcohol component such as glycerin, trimethylolpropane, trimethylolethane, pentaerythritol and the like may be used in combination as long as the polyester resin is not gelled.

The polyester resin of the present invention has a hydroxyl value of 10 to 80 mgKOH / g, preferably 15 to 75 mgKOH / g.
It must be KOH / g. Hydroxyl value is 10mgK
If it is less than OH / g, sufficient mechanical properties cannot be obtained. If it exceeds 80 mgKOH / g, the formed coating film is hard and brittle.

The polyester resin of the present invention has a number average molecular weight of 2,500 to 8,000, preferably 3,000 to 750.
Must be 0. If the number average molecular weight is less than 2500, sufficient mechanical properties cannot be obtained. Also, 8
When it exceeds 000, remarkable unevenness occurs on the surface of the formed coating film, so-called smoothness of the coating film is reduced.

The polyester resin of the present invention has a softening point of 1
It needs to be 00 to 135 ° C, preferably 105 to 130 ° C, and has a glass transition point of 35 to 75 ° C, preferably 4
It needs to be 0 to 70 ° C. When the softening point is less than 100 ° C. and / or the glass transition point is less than 35 ° C., particles are fused when powder coating is used, and blocking tends to occur. When the softening point exceeds 135 ° C. and / or the glass transition point exceeds 75 ° C., the smoothness of the coating film decreases.

Here, the above hydroxyl value is determined by acetylating the hydroxyl group of the polyester resin with a fixed amount of acetic anhydride in a pyridine solvent, and then hydrolyzing unreacted acetic anhydride.
This is a value determined by a method of back titrating the generated acetic acid with potassium hydroxide. Similarly, the above-mentioned number average molecular weight is a value measured by gel permeation chromatography (hereinafter abbreviated as GPC) using a polystyrene as a standard and obtaining a calibration curve. Further, the above softening point is determined by the ring and ball method (J
1SK2207). The above-mentioned glass transition point is a value measured by a differential scanning calorimetry (hereinafter abbreviated as DSC) based on alumina.

The polyester resin of the present invention is prepared by using a known acid component and an alcohol component as raw materials by a known and commonly used production method. At that time, either a transesterification reaction or a direct esterification reaction can be applied as a reaction method, and polycondensation can be promoted by a reduced pressure method or a method of flowing an inert gas under normal pressure.

In each of the above-mentioned reactions, a known and commonly used reaction catalyst can be used. In the present invention,
The polyester resin prepared as described above is mixed with an isocyanate-based curing agent as a curing agent that reacts with the polyester resin and various coating materials, and then melt-kneaded, cooled, then ground and classified. By doing so, it becomes a powder coating.

An isocyanate-based curing agent that constitutes a powder coating is generally an isocyanate compound in which the isocyanate group at the molecular end of the compound is blocked with a blocking agent so that the compound does not show activity at a certain temperature or lower. Although it is pointed out specifically, in the present invention, an isocyanate compound which does not show activity by self-blocking isocyanate groups without containing a blocking agent can also be used.

For example, aromatic, aliphatic and alicyclic isocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate and dimethylcyclohexane diisocyanate, or isocyanate groups contained in a prepolymer thereof, Representative examples include those blocked with a blocking agent such as a lactam compound and an oxime compound, and those in which the same isocyanate group is self-blocked by forming a uretdione ring.

More specifically, “Bestagon B153” manufactured by Huls, which is an isophorone diisocyanate-based curing agent having an isocyanate group blocked with ε-caprolactam, is used.
0 "and" Bestagon BF1540 ", an isophorone diisocyanate-based curing agent in which an isocyanate group is self-blocked by forming a uretdione ring.

Here, it is most preferable that the mixing ratio of the polyester resin and the isocyanate-based curing agent is the same as that of the isocyanate group of the isocyanate-based curing agent with respect to the hydroxyl group of the polyester resin, that is, 1 equivalent ratio. , 0.5 to 1.5. If the equivalent ratio is out of the above range and less than 0.5, sufficient mechanical properties cannot be obtained, and if it exceeds 1.5, the formed coating film becomes hard and brittle.

Further, the powder coating material of the present invention may be used as various known and commonly used coating materials, such as a pigment or other filler such as titanium dioxide, a pinhole inhibitor such as benzoin, and a polyacrylate or silicone leveling agent. The resulting powder coating composition comprises an agent and a curing catalyst such as an organotin compound. The resulting powder coating is applied to a metal substrate by a known and common electrostatic coating method, and then baked to form a cured coating film.

[0036]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Here, the raw material composition described in the following text first indicates parts by weight of the preparation of each raw material, and then the mol% in the total acid component or the total alcohol component is indicated in parentheses. The blocking resistance and the coating film performance of the powder coatings in Examples and Comparative Examples were evaluated by the following test methods.

Test Method "Blocking resistance" 20 g of powder coating was applied with a diameter of 25 mm.
Gently fill a closed PVC pipe with one end of height 150mm,
Slowly insert a 66g PVC rod from above to load (approximately 1
3.5 g / cm ² ), and stand it upright.
After standing for 7 days in a thermostat at 5 ° C., the contents were gently taken out, and the condition was observed and evaluated as follows. Excellent and good were passed. Excellent: There are no lumps in the powder coating, and the powder coating remains smooth. Good: Even if there is a lump in the powder coating, it breaks and returns to a powdery state when touched by hand. Poor: The powder coating fuses to form a lump, which does not break even if you hold it by hand.

"60 degree specular gloss" The specular gloss of JlSK5400 was used. 90% or more was regarded as a pass.

"Impact resistance" According to the impact resistance (du Pont type) of J1SK5400. A 500 g weight was dropped from a prescribed height, and cracks and peeling of the coating film were observed. Height 50
If the coating film did not crack or peel off in cm, it was accepted.

"Erichsen value" The Erichsen value of JlSK5400 (breaking distance method) was used. Extrude a steel ball,
Cracks and peeling of the coating film were observed. Even if the extrusion was 5 mm or more, the coating film without any cracking or peeling was judged to be acceptable.

"Accelerated weathering resistance" According to the accelerated weathering resistance (sunshine carbon arc lamp type) of J1SK5400. 1
The gloss retention after the test for 500 hours was determined, and 80% or more was regarded as acceptable.

Example 1 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 1 in Table 1 below, neopentyl glycol 78 was used as a raw material alcohol component for preparing a polyester resin.
5 parts (72 mol), 428 parts (20 mol) of "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, and 112 parts (8 mol) of trimethylolpropane were mixed with a stirring device, a heating device, a thermometer,
The mixture was charged into a stainless steel reaction vessel equipped with a fractionating apparatus and a nitrogen gas inlet tube, and heated to 160 ° C. with stirring to melt the contents.

After the melting, as shown in Example 1 of the same table, half of 830 parts (50 moles) of isophthalic acid and 0.75 part of di-n-butyltin oxide were charged as raw material acid components, and While the temperature at the top does not exceed 100 ° C., while the condensed water generated is removed from the system by a nitrogen gas stream, the temperature is gradually raised to 240 ° C. to carry out the esterification reaction, and the amount of condensed water generated is reduced. Cool to 180 ° C. after over 90% of theory.

After cooling, 830 parts (50 moles) of the remaining half of the isophthalic acid shown in Example 1 in the same table were charged, and while the condensed water was removed from the system by the same operation as described above, the mixture was gradually cooled to 2 parts.
The temperature was raised to 40 ° C., and the reaction was continued at that temperature. At any time during the reaction, a part of the reaction product is collected and dissolved in pyridine, and then the alcoholic KOH solution (1/1) is used.
The acid value was measured by a titration method (0 normal), and the reaction was continued until this value became 5 or less to obtain a polyester resin. The characteristic values of the polyester resin obtained in Example 1 are as follows:
As shown in Table 1 below, the acid value is 4, the hydroxyl value is 33, the number average molecular weight is 5,500, the softening point is 120 ° C, and the glass transition point is 57.
° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 1 in Table 1 below, polyester resin 8 prepared as described above was used as a raw material for preparing powder coating.
59 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
141 ", rutile type titanium dioxide pigment" Taipek CR-90 "manufactured by Ishihara Sangyo Co., 400 parts, benzoin 5
First, FM: 6 parts of a polyacrylate-based leveling agent "Polyflow S" manufactured by Kyoeisha Chemical Co., Ltd. and 3 parts of an organic tin compound-based curing catalyst "Formate TK-1" manufactured by Takeda Pharmaceutical Co., Ltd.
The mixture was dry-blended with a 20C / I type Mitsui Henschel mixer, then melt-kneaded at 110 ° C. with a PLK46 type Buss kneader, cooled, pulverized, and classified with a 150 mesh wire mesh to obtain a powder coating.

The powder coating prepared as described above is coated on a zinc phosphate-treated steel sheet using an electrostatic powder coating machine, and
By baking at 80 ° C for 20 minutes, a film thickness of 50 to 6
A cured coating of 0 μm was obtained. With respect to this cured coating film and the above powder coating, the above-mentioned various properties were examined. As shown in Example 1 in Table 1 below, the evaluation results of the performance were that the gloss retention after 1500 hours was 88%, and the Erichsen value was 5 mm. The polyester resin for powder coating and the powder coating of Example 1 contained 20 mol% of "ester glycol" manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. It showed excellent weather resistance and mechanical properties.

Example 2 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 2 in Table 1 below, 97 parts (15 mol) of ethylene glycol was used as a raw material alcohol component for preparing a polyester resin, and Mitsubishi Gas Chemical Co., Ltd. A polyester resin was obtained in the same manner as in Example 1 except that 1738 parts (82 mol) of “Ester Glycol” and 42 parts (3 mol) of trimethylolpropane were charged. The characteristic values of the polyester resin obtained in Example 2 are shown in Table 1 below.
As shown in Table 1, the acid value is 3, the hydroxyl value is 10, and the number average molecular weight is 7.
500, softening point 113 ° C., and glass transition point 45 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 2 in Table 1 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
52 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
All were carried out in the same manner as in Example 1 except that 48 parts of "30" were used to obtain a powder coating and a cured coating film. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Example 2 in Table 1 below, the evaluation results of the performance were that the gloss retention after 1500 hours was 83%, and the Erichsen value exceeded 7 mm. The polyester resin for powder coating and the powder coating of Example 2 contained 82 mol% of "ester glycol" manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. It showed excellent weather resistance and mechanical properties.

Example 3 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 3 in Table 1 below, neopentyl glycol 83 was used as a raw material alcohol component for preparing a polyester resin.
2 parts (77 mol), 97 parts (15 mol) of ethylene glycol, "Pespol HP-1000" 27 manufactured by Toagosei Co., Ltd.
A polyester resin was obtained in the same manner as in Example 1 except that 8 parts (5 mol) and 29 parts (3 mol) of glycerin were charged. As shown in Table 1 below, the characteristic values of the polyester resin obtained in Example 3 were an acid value of 3.5, a hydroxyl value of 18, a number average molecular weight of 6,500, a softening point of 110 ° C,
The glass transition point was 48 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 3 in Table 1 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
18 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
30 and 82 parts, except that powder coating and a cured coating film were obtained in the same manner as in Example 1 described above. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Example 3 in Table 1 below, the evaluation results of the performance were that the gloss retention after 1500 hours was 81% and the Erichsen value exceeded 7 mm. The polyester resin for powder coating and the powder coating of Example 3 are “Pespol HP-” manufactured by Toagosei Co., Ltd., which is a diol unit having a molecular weight of 200 or more as an alcohol component constituting the polyester resin.
By containing 5 mol% of "1000", excellent weather resistance and mechanical properties were exhibited.

Example 4 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 4 in Table 1 below, neopentyl glycol 10 was used as a raw alcohol component for preparing a polyester resin.
27 parts (95 mol), 85 parts (4 mol) of "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, and 56 parts (1 mol) of "Pespol HP-1000" manufactured by Toagosei Co., Ltd. 830 parts (50 moles) of isophthalic acid were charged and reacted, and after cooling, the remaining 780 parts (47 moles) of isophthalic acid and trimellitic anhydride 5
A polyester resin was obtained in the same manner as in Example 1 except that 8 parts (3 moles) were charged. Example 4
As shown in Table 1 below, the characteristic values of the polyester resin obtained in Example 1 were an acid value of 4.2, a hydroxyl value of 20, and a number average molecular weight of 65.
The softening point was 123 ° C and the glass transition point was 59 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 4 in Table 1 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
09 parts, ル -caprolactam-blocked isophorone diisocyanate-based curing agent “Vestagon B15” manufactured by Huls Co.
30 and 91 parts were used, except that a powder coating and a cured coating were obtained in the same manner as in Example 1 described above. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Example 4 in Table 1 below, the evaluation results of the performance were that after 1500 hours, the gloss retention was 85%, and the Erichsen value was 7 mm. The polyester resin for powder coating and the powder coating of Example 4 used "ester glycol" manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin.
Mol%, and "Pespol HP-100" manufactured by Toagosei Co., Ltd.
By containing 1 mol% of "0", excellent weather resistance and mechanical properties were exhibited.

Example 5 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 5 in Table 1 below, neopentyl glycol 97 was used as a raw material alcohol component for preparing a polyester resin.
4 parts (87 mol), 110 parts (5 mol) of "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, trimethylolpropane 2
After 9 parts (2 mol) and 59 parts (6 mol) of glycerin were charged and melted, 332 parts (20 mol) of isophthalic acid and 498 parts (30 parts) of terephthalic acid were used as raw acid components.
Mol), and after cooling, the same procedure as in Example 1 was carried out except that the remaining 830 parts (50 mol) of isophthalic acid were charged to obtain a polyester resin.
As shown in Table 1 below, the characteristic values of the polyester resin obtained in Example 5 were an acid value of 5, a hydroxyl value of 57, a number average molecular weight of 4000, a softening point of 115 ° C, and a glass transition point of 60 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 5 in Table 1 below, polyester resin 77 prepared as described above was used as a raw material for preparing powder coating.
9 parts, ル -caprolactam-blocked isophorone diisocyanate-based curing agent “Vestagon B153” manufactured by Huls Co.
Except for using 221 parts of "0", the same procedure as in Example 1 was carried out to obtain a powder coating and a cured coating film. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Example 5 in Table 1 below, the evaluation results of the performance were that the gloss retention after 1500 hours was 80%, and the Erichsen value was 6 mm. The polyester resin for powder coating and the powder coating of Example 5 are excellent by containing 5 mol% of “ester glycol” manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. It showed excellent weather resistance and mechanical properties.

Example 6 [Preparation and Characteristic Values of Polyester Resin] As shown in Example 6 in Table 1 below, neopentyl glycol 83 was used as a raw alcohol component for preparing a polyester resin.
Except that 2 parts (77 mol), 97 parts (15 mol) of ethylene glycol, 125 parts (5 mol) of "Rikabinol HB" manufactured by Nippon Rika Co., Ltd., and 29 parts (3 mol) of glycerin were all charged, and all the above-mentioned examples were used. In the same manner as in Example 1, a polyester resin was obtained. As shown in Table 1 below, the characteristic values of the polyester resin obtained in Example 6 were an acid value of 3.1, a hydroxyl value of 18, a number average molecular weight of 7000, a softening point of 128 ° C, and a glass transition point of 65 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Example 6 in Table 1 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
18 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
30 and 82 parts, except that powder coating and a cured coating film were obtained in the same manner as in Example 1 described above. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Example 6 in Table 1 below, the performance evaluation result was that the gloss retention after 1500 hours was 83%, and the Erichsen value was 5 mm. The polyester resin for powder coating and the powder coating of Example 6 contained 5 mol% of "Rikabinol HB" manufactured by Shin Nippon Rika Co., Ltd., which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. It showed excellent weather resistance and mechanical properties.

Comparative Example 1 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 1 in Table 2 below, 32 parts of ethylene glycol (5
Mol), Mitsubishi Gas Chemical Company's “Ester Glycol” 19
A polyester resin was obtained in the same manner as in Example 1 except that 50 parts (92 mol) and 42 parts (3 mol) of trimethylolpropane were charged. The characteristic values of the polyester resin obtained in Comparative Example 1 were, as shown in Table 2 below, an acid value of 2.9, a hydroxyl value of 10, and a number average molecular weight of 750.
0, softening point 99 ° C, glass transition point 40 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 1 in Table 2 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
62 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
30 and 38 parts, except that all were used in the same manner as in Example 1 to obtain a powder coating and a cured coating film. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 1 in Table 2 below, the evaluation result of the performance was that the powder coating had poor blocking resistance and a gloss retention after 1,500 hours of 76%. The polyester resin for powder coating and the powder coating of Comparative Example 1 contained 92 mol% of an appropriate amount of "ester glycol" manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. Therefore, the softening point was less than 100 ° C., the blocking resistance was poor, and the target weather resistance was not reached.

Comparative Example 2 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 2 in Table 2 below, neopentyl glycol 10 was used as a raw material alcohol component for preparing a polyester resin.
77 parts (99.7 mol), “Pespol H” manufactured by Toagosei Co., Ltd.
After charging 17 parts (0.3 mol) of P-1000 and melting it, a part of 830 parts (50 mol) of isophthalic acid as a raw acid component was charged and reacted, and after cooling, the remaining 780 parts of isophthalic acid (47 mol) and trimellitic anhydride 5
A polyester resin was obtained in the same manner as in Example 1 except that 8 parts (3 moles) were charged. Comparative Example 2
As shown in Table 2 below, the characteristic values of the polyester resin obtained in Example 2 were an acid value of 4, a hydroxyl value of 21, and a water average molecular weight of 65.
The softening point was 126 ° C and the glass transition point was 64 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 2 in Table 2 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
05 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
All were carried out in the same manner as in Example 1 except that 95 parts of "30" were used to obtain a powder coating and a cured coating film. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 2 in Table 2 below, the evaluation result of the performance was an Erichsen value of 2 mm. The polyester resin for powder coating and the powder coating of Comparative Example 2 had a molecular weight of 200 as an alcohol component constituting the polyester resin.
"Pespol H" manufactured by Toagosei Co., Ltd.
Since P-1000 was contained in less than an appropriate amount of 0.3 mol%, the target mechanical properties were not reached.

Comparative Example 3 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 3 in Table 2 below, neopentyl glycol 83 was used as a raw material alcohol component for preparing a polyester resin.
Except that 2 parts (77 mol), 97 parts (15 mol) of ethylene glycol, 47 parts (5 mol) of 1,4-butanediol, and 29 parts (3 mol) of glycerin were used, all were the same as in Example 1 described above. And a polyester resin was obtained.
As shown in Table 2 below, the characteristic values of the polyester resin obtained in Comparative Example 3 were an acid value of 3, a hydroxyl value of 18, a number average molecular weight of 7000, a softening point of 130 ° C, and a glass transition point of 68 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 3 in Table 2 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
18 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
30 and 82 parts, except that powder coating and a cured coating film were obtained in the same manner as in Example 1 described above. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 3 in Table 2 below, the results of the performance evaluation were that the impact resistance was 40 cm and the Erichsen value was 2 mm. Since the polyester resin for powder coating and the powder coating of Comparative Example 3 did not contain any diol unit having a molecular weight of 200 or more as an alcohol component constituting the polyester resin, the target mechanical properties were not reached.

Comparative Example 4 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 4 in Table 2 below, neopentyl glycol 66 was used as a raw material alcohol component for preparing a polyester resin.
Except that 1 part (60 mol), 432 parts (20 mol) of "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, and 284 parts (20 mol) of trimethylolpropane were charged, all were carried out in the same manner as in Example 1 described above. A polyester resin was obtained. As shown in Table 2 below, the characteristic values of the polyester resin obtained in Comparative Example 4 were an acid value of 5, a hydroxyl value of 83, a number average molecular weight of 4000, a softening point of 114 ° C, and a glass transition point of 56 ° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 4 in Table 2 below, polyester resin 73 prepared as described above was used as a raw material for preparing powder coating.
6 parts, ル -caprolactam-blocked isophorone diisocyanate-based curing agent “Vestagon B153” manufactured by Huls Co.
Except that 264 parts of "0" were used, all were carried out in the same manner as in Example 1 to obtain a powder coating material and a cured coating film. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 4 in Table 2 below, the results of the performance evaluation were that the impact resistance was 30 cm and the Erichsen value was 1 mm. The polyester resin for powder coating and the powder coating of Comparative Example 4 contain an appropriate amount of 20 mol% of “ester glycol” manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. Since the hydroxyl value exceeded 80, the target mechanical properties could not be realized.

Comparative Example 5 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 5 in Table 2 below, neopentyl glycol 99 was used as a raw material alcohol component for preparing a polyester resin.
1 part (87 mol), 112 parts (5 mol) of "Ester Glycol" manufactured by Mitsubishi Gas Chemical Company, trimethylolpropane 2
After 9 parts (2 mol) and 60 parts (6 mol) of glycerin were charged and melted, 332 parts (20 mol) of isophthalic acid and 498 parts (30 parts) of terephthalic acid were used as raw acid components.
Mol), and after cooling, the same procedure as in Example 1 was carried out except that the remaining 830 parts (50 mol) of isophthalic acid were charged to obtain a polyester resin.
The characteristic values of the polyester resin obtained in Comparative Example 5 were, as shown in Table 2 below, an acid value of 4.5, a hydroxyl value of 62, a number average molecular weight of 2,300, a softening point of 110 ° C, and a glass transition point of 59 ° C.
Met.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 5 in Table 2 below, polyester resin 76 prepared as described above was used as a raw material for preparing powder coating.
4 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B153
Except that 236 parts of "0" were used, the same procedure was carried out as in Example 1 to obtain a powder coating and a cured coating. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 5 in Table 2 below, the results of the performance evaluation were that the impact resistance was 30 cm and the Erichsen value was 3 mm. The polyester resin for powder coating and the powder coating of Comparative Example 5 contain an appropriate amount of 5 mol% of “ester glycol” manufactured by Mitsubishi Gas Chemical Company, which is a diol unit having a molecular weight of 200 or more, as an alcohol component constituting the polyester resin. Since the number average molecular weight was less than 2500, the target mechanical properties could not be realized.

Comparative Example 6 [Preparation and Characteristic Values of Polyester Resin] As shown in Comparative Example 6 in Table 2 below, 64 parts (10 mol) of ethylene glycol was used as a raw material alcohol component for preparing a polyester resin, and Mitsubishi Gas Chemical Co., Ltd. Except that 1738 parts (82 mol) of “Ester Glycol”, 278 parts (5 mol) of “Pespol HP-1000” manufactured by Toagosei Co., Ltd., and 42 parts (3 mol) of trimethylolpropane were used. In the same manner as in Example 1, a polyester resin was obtained. The characteristic values of the polyester resin obtained in Comparative Example 6 are as follows:
As shown in Table 2 below, an acid value of 3.4, a hydroxyl value of 18, a number average molecular weight of 6,500, a softening point of 91 ° C, and a glass transition point of 33.
° C.

[Preparation of Powder Coating and Evaluation of Performance] As shown in Comparative Example 6 in Table 2 below, polyester resin 9 prepared as described above was used as a raw material for preparing powder coating.
18 parts, Huls ε-caprolactam blocked isophorone diisocyanate-based curing agent “Vestagon B15
30 and 82 parts, except that powder coating and a cured coating film were obtained in the same manner as in Example 1 described above. The above-mentioned various properties were examined for the powder coating and the cured coating film. As shown in Comparative Example 6 in Table 2 below, the evaluation result of the performance was that the powder coating had poor blocking resistance and a gloss retention after 1500 hours of 71%. The polyester resin for powder coating and the powder coating of Comparative Example 6 were manufactured by Mitsubishi Gas Chemical Co., Ltd., "Ester Glycol" and Toagosei Co., Ltd. "Pespol HP", which are diol units having a molecular weight of 200 or more as alcohol components constituting the polyester resin. -100
Since “0” contained 87 mol% exceeding the appropriate amount in total, the softening point was less than 100 ° C. and the glass transition point was less than 35 ° C., so that the blocking resistance was poor and the target weather resistance was not reached.

[0069]

[Table 1]

[0070]

[Table 2]

[0071]

As described above, since the present invention is constituted, polyester resin for powder coating which can form a coating film having excellent long-term weather resistance and excellent mechanical properties. And an effect of obtaining a powder coating.

Claims (3)

[Claims] 1. The acid component is mainly composed of isophthalic acid, the alcohol component is composed of 15 to 99.5 mol% of neopentyl glycol and / or ethylene glycol, and 0.5 to 85 mol% of a diol unit having a molecular weight of 200 or more. A hydroxyl value of 10 to 80 mgKOH / g, a number average molecular weight of 2500 to 8000, a softening point of 100 to 135 ° C,
Polyester resin for powder coating having a glass transition point of 35 to 75 ° C. 2. The polyester resin according to claim 1, wherein the diol unit having a molecular weight of 200 or more constituting the polyester resin is 2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-diol.
3-hydroxypropionate and / or C36
Polyester resin for powder coatings, which is a dimer diol and / or hydrogenated bisphenol A. 3. A powder coating comprising the polyester resin for powder coating according to claim 1 and an isocyanate-based curing agent and a coating material.