JP2003528200A - Carboxyl-functional polyester epoxy resin powder coating containing 1,3-propanediol as a main component - Google Patents

Abstract

  (57) [Summary] a) A polyester resin obtained by reacting one or more aliphatic glycols with one or more polycarboxylic acids and / or anhydrides in the presence of an esterification catalyst, wherein the polyester has a carboxyl chain terminal. And b) reacting a polyester resin end-capped with an end-capping agent and b) an epoxy resin cross-linking agent, wherein the aliphatic glycol is 5 to 90% 1,3 on a molar basis. A polyester powder coating composition comprising propanediol.

Description

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to powder coating of epoxy resin crosslinked polyesters. More specifically, the present invention relates to a polyester, 1,3-propanediol (1,3-, which is commonly used for carboxyl functional polyester-epoxy coatings.
PDO) significantly improves flexibility and impact resistance, and other important properties relate to modifications that do not change over a wide range of 1,3-PDO concentrations. further,
Polyester modified with 1,3-PDO has a lower melt viscosity than polyester made with 100% neopentyl glycol.

BACKGROUND OF THE INVENTION The development of powder coatings has become increasingly important in recent years. Powder coatings, which do not release harmful solvents during application, can be applied in a very efficient manner with low waste, and are therefore regarded as particularly environmentally friendly and economical. Useful powder coatings can be obtained by using curable epoxy resin powder coatings. Many types of epoxy resin powder coatings currently on the market contain solid polyester polyols that cure with epoxy resins.

Polymers used in the manufacture of powder coatings are broadly classified as either thermosetting or thermoplastic. Compared to coatings derived from thermoplastic compositions, thermosetting coatings are generally tougher, more resistant to solvents and detergents, have better adhesion to metallic substrates, and when exposed to high temperatures. Does not soften. However, when curing a thermosetting coating,
In addition to the desired properties mentioned above, problems arise in obtaining coatings with good smoothness and flexibility.

Thermosetting powder coatings can be classified into epoxies, epoxy-polyesters, polyester-urethanes, TGIC polyesters, and acrylics. Epoxy-polyester coatings have better color retention and UV resistance than epoxy powder coatings. Such coatings include furniture furniture such as refrigerators, freezers, washing machines, stoves, and other kitchen appliances, metal furniture, ceiling panels for the building industry, shower cabinets, automotive parts, agricultural equipment, and mechanical parts, Widely used in industrial and electrical parts.

Coatings derived from thermosetting coating compositions should have excellent impact strength, hardness, flexibility, and resistance to solvents and chemicals. For example, for the coating of sheet (coil) steels intended to be formed into articles used in the manufacture of various household appliances and automobiles that bend and bend sheet metal at various angles. It is important for the powder coating composition to be excellent in flexibility.

Carboxyl polyesters, such as neopentyl glycol-based carboxyl polyesters, and powder coating systems based on melamine-formaldehyde, benzoguanamine-formaldehyde, and urea-formaldehyde crosslinkers have been used in the coating industry. For example, US Pat. No. 57392.
See the description of No. 04. EP 0008344 discloses a similar system and also mentions the use of 1,3-PDO.

[0007] Neopentyl glycol is often used as a formulation for polyester powder coatings, with which a mixture of terephthalic acid and isophthalic acid may themselves or as a mixture branched with a small amount of trimethylolpropane. used. When modifying the polyesters used in this type of powder coating to generally improve flexibility, impact strength, and toughness, other properties important to the coating are impaired. Other potentially useful modifiers include:
Examples include adipic acid, 1,4-butanediol, and 2-methyl-1,3-propanediol.

1,3-Carboxyl-functional polyester epoxy resin powder coating compositions for improving impact resistance and flexibility without compromising other important properties.
The incorporation of propanediol is not described in any prior art references, and also that 1,3-PDO modified polyesters have lower melt viscosities than polyesters derived from 100% neopentyl glycol. Not mentioned.

(Summary of the Invention) From the above, the present invention comprises: a) one or more kinds of aliphatic glycols and one or more kinds of polycarboxylic acids and / or
Alternatively, an anhydride is reacted in the presence of an esterification catalyst, and a polyester resin obtained by endcapping the obtained polyester with an endcapping agent so that the polyester has a carboxyl chain end, and b) an epoxy resin crosslinker, Obtained by reacting, the aliphatic glycol is 5 to 90% on a molar basis.
Polyester powder coating composition comprising 1,3-propanediol.

The partial replacement of neopentyl glycol with 1,3-propanediol improves the impact resistance and flexibility of the formulation over a wide range of 1,3-propanediol concentrations and other important properties. Does not change substantially, 1,3-PDO
It was found that the polyester modified by 1. had a lower melt viscosity than the polyester synthesized with 100% neopentyl glycol.

According to the invention: a) a mixture of neopentyl glycol and 1,3-propanediol (1,3-
Propanediol constitutes 5 to 90% of the mixture on a molar basis) and a mixture of terephthalic acid and isophthalic acid (the ratio of terephthalic acid to isophthalic acid is 90/10).
To 50/50) in the presence of dibutyltin oxide, and a polyester resin obtained by endcapping with the addition of trimellitic anhydride, and b) bisphenol A pre-reacted with epoxy. Provided is a polyester powder coating composition obtained by reacting with an epoxy resin cross-linking agent which is a diglycidyl ether of 2,2-bis (4-hydroxyphenyl) propane having a molecular weight of 450 to 900 per unit. To do.

According to the present invention, there is further provided any coated product produced using the powder coating composition of the present invention.

[0013]     (Brief description of drawings)   The invention will be described by way of example with reference to the accompanying drawings.

[0014]   FIG. 1 is a graph showing the glass transition temperature of various formulations.

FIG. 2 is a graph showing a differential scanning calorimetry (DSC) curve of a carboxypolyester resin.

FIG. 3 shows the differential scanning calorimetry (D / D) of the polyester / epoxy composite powder coating.
(SC) is a graph showing a curve.

FIG. 4 is a graph showing the gloss of clear and pigmented polyester / epoxy powder coatings.

DETAILED DESCRIPTION OF THE INVENTION In the present invention, an aliphatic glycol, which is preferably neopentyl glycol (NPG), is added in an amount of 5 to 90%, preferably 10 to 50%, of 1,3-propanediol on a molar basis. Replacing with (1,3-PDO) significantly improved the impact resistance and flexibility of the epoxy resin crosslinked polyester powder coating, while at the same time other properties were similar to the control sample using 100% NPG. Next to
It was also discovered that the polyester modified with 1,3-PDO had a lower melt viscosity than the polyester obtained from 100% neopentyl glycol. The properties investigated for the polyester capped with carboxyl groups are carboxy equivalent, acid value, color before crushing, glass transition temperature (T _g ), processability, storage stability, front / back surface impact resistance, powder flow characteristics, Powder reactivity, hardness, adhesion, MEK double rubs, and chemical and stain resistance.

A preferred carboxyl-capped polyester has an acid value of 30 to 120 mgK.
OH / g, preferably 40 to 110 mg KOH / g, with the property that the T _g is above 40 ° C. Acid value = 56,100 / equivalent (56,100 is 1
(Weight per mole KOH (unit mg)). When the equivalent weight is low and the acid value is high, the crosslink density is high and brittle, and when the equivalent weight is high or the acid value is low, the crosslink density is low, and thus performances such as resistance to methyl ethyl ketone and a solvent are deteriorated.
The above T _g range is generally necessary to obtain good storage stability.

The starting materials for the polyesters of the present invention are aliphatic glycols such as 1,3-PDO, aromatic polycarboxylic acids or anhydrides, esterification catalysts and optionally branching agents. The starting materials for the cured coatings of the present invention are 1,3-PDO-containing polyesters, one or more epoxy resins, crosslinking catalysts, and optional modifiers, auxiliaries and additives.

Suitable aliphatic glycols have a number average molecular weight of 62 to 500 and may optionally contain ether units, ester groups, and / or carbonate groups. Suitable aliphatic glycols include ethylene glycol, 1,2-propanediol,
Examples include 2-methyl-1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, and mixtures of these diols. However, the present invention is not limited to these. Other suitable diols include triethylene glycol, tetraethylene glycol, tripropylene glycol, tetrapropylene glycol, polycarbonate diols having a hydroxyl number of about 56 to 168, dimeric fatty alcohols, and mixtures of these diols. To be The reactive hydroxyl component (carboxyl, amide) may be a simple monomer unit or an oligomer unit or a low molecular weight polymer unit. Preferred glycols are 1,3-butylene glycol or 1,4-butylene glycol, ethylene glycol and propylene glycol, and aliphatic glycols such as neopentyl glycol. Neopentyl glycol is most preferred and was used in the examples of the invention. Small amounts of trihydric or higher alcohols are also useful, as described below.

Suitable acids include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, maleic acid, fumaric acid, succinic acid, adipic acid, azelaic acid, malonic acid, dodecanedioic acid, trimellitic acid, pyromellitic acid. , And similar polycarboxylic acids, or mixtures thereof, such as saturated, unsaturated, aliphatic, or aromatic polycarboxylic acids and / or anhydrides. Preferred polycarboxylic acids and / or anhydrides in the present invention are isophthalic acid, terephthalic acid, and trimellitic acid, and their anhydrides, which may be used alone or as a mixture. Preference is given to using in acid form in this reaction step. Most preferred is a mixture of terephthalic acid and isophthalic acid in a molar ratio of 90/10 to 50/50.

Branching agents such as small amounts of triols or alcohols with a valence of 4 or more are also useful. Suitable branching agents include, but are not limited to, trimethylolethane, trimethylolpropane, or pentaerythritol. Trimethylolpropane was preferred.

The carboxyl functional polyester of the present invention may be synthesized in a two step process. This is an esterification reaction. In the first step, a dibasic acid such as terephthalic acid (TPA) or isophthalic acid (IPA), a polyol such as NPG or PDO diol, and an optional branching agent such as trimethylolpropane are added in the range of 150 to 250 ° C. At a temperature of, preferably in the range 170 to 230 ° C. to produce a hydroxyl terminated prepolymer.

In the second step, the hydroxyl groups are end-capped with carboxylic acids or their anhydrides to form acid polyesters. The amount of endcapping agent used depends on the hydroxyl number of the polyester. 80 to 100% of the stoichiometric amount required to cap all polyester chain ends is generally added.
Endcapping agents that can be used generally have a plurality of carboxylic acid groups, ie 1
An acid or anhydride containing two or more carboxylic acid groups per molecule. Suitable acids include saturated, unsaturated, aliphatic or aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, maleic acid, fumaric acid, succinic acid, adipic acid, azelaine. Acids, malonic acid, dodecanedioic acid, trimellitic acid, pyromellitic acid, or mixtures thereof. Terephthalic acid is preferred, and isophthalic acid is more preferred. If these acid anhydrides are present, they can also be used as the endcapping agent, and preferably include the above acid anhydrides, such as phthalic anhydride, trimellitic anhydride, and succinic anhydride. Is particularly preferable, and trimellitic anhydride is preferable among them.
The endcapping agent is added to the prepolymer and esterification is continued until the desired acid number is obtained. The total reaction time is approximately 10 to 15 hours.

Conventional catalysts such as dibutyltin oxide for promoting the esterification reaction are:
It can be used in catalytic amounts of 0.01 to 1% by weight. This catalyst may be added in either the first stage or the second stage. As a catalyst that can be used for esterification,
Examples include compounds of tin, antimony, titanium, and zirconium, for example,
Tetra (2-ethylhexyl) titanate, tetrastearyl titanate, diisopropoxy-bis (acetylacetonato) titanium, di-n-butoxy-bis (triethanolaminoat) titanium, tributyl monoacetyltitanate, monoacetyltitanium. Acid triisopropyl and titanium alkoxides and derivatives thereof such as tetrabenzoic acid titanate, alkali titanium oxalates and malonates, and titanium complex salts such as potassium hexafluorotitanate, and hydroxycarboxylic acids such as tartaric acid, citric acid, or lactic acid. Titanium complex with, titanium dioxide /
Included are catalysts such as silicon dioxide coprecipitates and hydrated alkali-containing titanium dioxide, as well as the corresponding zirconium compounds.

To facilitate the removal of water formed during the reaction, xylene /
Water may be added. In the examples, neopentyl glycol is replaced with 1,3-propanediol in molar increments of 0, 15, 30, 50, and 100%.

As will be apparent to those skilled in the art, there are other ways to carry out the reaction. The use of xylene / water is probably rare in industrial scale reactions and esters such as dimethyl terephthalate (DMT) or dimethyl isophthalate (DMI) can be used to initiate the reaction. Acid chlorides can also be used.

Powder coatings can be prepared by incorporating a polyester derived from 1,3-propanediol with an epoxy resin crosslinking agent, a flow control agent, and a crosslinking catalyst. Conventional coloring materials (pigments or dyes), such as titanium dioxide, can also be added to the formulation to color the coated substrate as desired.

Generally, suitable epoxy resins for the compositions of the present invention are any epoxy resin that is solid at room temperature. The epoxy resin has an average molecular weight per epoxide (WP
E) is in the range of 400 to 1400 and the number average molecular weight is 800 to 5000.
It is preferably within the range. More preferably, the epoxy resin has a WPE of 50.
The number average molecular weight is 1000 to 2000. Higher WPEs and molecular weights can also be used provided that the resins are mixed at the processing temperature and can be processed in a high shear mixer or melt blender.

In general, these epoxy resins have a 1,2-epoxy equivalent weight of more than 1, preferably about 2 or more. It may be an epoxy resin, saturated or unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic. Examples of epoxy resins suitable for use in the present invention include polyglycidyl ethers of polyhydroxy compounds, brominated epoxies, epoxy novolacs or similar polyhydroxyphenolic resins, polyglycidyl ethers of glycols or polyglycols, and polycarboxylic acids. Polyglycidyl ester of. Preferably, the epoxy resin is a polyglycidyl ether of polyhydric phenols. Polyglycidyl ethers of polyhydric phenols can be produced, for example, by reacting epihalohydrin and polyhydric phenol in the presence of alkali. Examples of suitable polyphenols include 2,2-
Bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxy-tert-butylphenyl) propane, 1,1-bis (4-
Hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) isobutane, 2,2-bis (4-hydroxytert-butylphenyl) propane, bis (2-hydroxynaphthyl) methane, 1,5-dihydroxynaphthalene, And 1,1-bis (4-hydroxy-3-alkylphenyl) ethane. A preferred polyhydric phenol is bisphenol A. The preferred epoxy resin is reacted with bisphenol A and has a molecular weight of 450 to 900 per epoxy.
Is a diglycidyl ether of 2,2-bis (4-hydroxyphenyl) propane. Commercially available examples of suitable epoxy resins include modified EPO (EPO).
N) ™ Resin 828, which is a product of Shell Chemical Company, which has an average molecular weight of 380 and a molecular weight of 180 to 195 per epoxy.
Which is within the range of 2,2-bis (4-hydroxyphenyl) propane diglycidyl ether. Preferred crosslinking agents are Epon Resin 1001F, 1002F
, And 2002, which have a molecular weight of 450 to 9 per epoxy.
Modified Epon 828 resin reacted with 00 bisphenol A.

Flow control agents or leveling agents are desirably incorporated into the coating formulation to facilitate smoothing of the applied and heat cured coatings. Such rheology modifiers, which typically include acrylic polymers, are available from several sources, namely Monsanto Company.
) MODAFLOW, BYK Mallincrod
t) BYK 360P and BASF's ACRONAL are available.
The preferred concentration range of the flow modifier incorporated into the coating is 0.25 to 2.0%, preferably 0.60 to 1.5%, based on the weight of resin solids.

The powder coating can be cured or crosslinked without the use of catalysts. However, it has been found that a catalyst is practically needed to accelerate the crosslinking reaction between the epoxy resin and the polyester. It has been found that the reaction rate in the absence of a catalyst is too slow to meet the baking regimes established in the industry. Suitable catalysts include amine-containing compounds such as amides, imides, imidazoles, quaternary ammonium salts, phosphonium salts, metal salts of acidic fatty acids, tin and zinc compounds. Specific examples of these catalysts are tetrabutylammonium and choline chloride. These catalysts can be used either alone or in combination of two or more. Further, the type and amount of catalyst used will vary with the type and amount of resin and curing conditions,
Careful selection is required to match the required performance. The preferred concentration range of catalyst incorporated into the coating is 0.01 to 1%, preferably 0.05 to 0.5%, based on the weight of resin solids.

Example Synthesis of Carboxyl Functional Polyester A two-step process was used to synthesize the carboxyl functional polyester. In the first stage, terephthalic acid (TPA), isophthalic acid (IPA), NPG, and PDO were reacted at 170 to 230 ° C. in a 1 liter round bottom flask under a nitrogen atmosphere to obtain a prepolymer. In the second stage, trimellitic anhydride (TMA) was added,
Esterification was continued from an acid number of 100 to 110. The total reaction time was about 10 to 15 hours. Xylene / water was added to use dibutyltin oxide (0.4%) as a catalyst to facilitate removal of water formed during the reaction. 0 to 10 on a molar basis
A polyester composition in which NPG is replaced with PDO at 0% is shown in Table 1.

[0035]

[Table 1]

Preparation of Powder Coating A polyester / epoxy composite powder coating was prepared by blending a PDO-derived polyester with an epoxy resin so that the carboxy groups / epoxy groups had the same equivalent weight. Shell Chemical Company Epon 1001 with an equivalent weight of 525 to 550
F resin was used as a crosslinking agent for the polyester. Epon 1001F resin has a very low equivalent weight among commercially available epoxy resins. 0.2% choline chloride (Actiron CC-6 from Synthron, Inc.)
Was used as the catalyst. Flow control agent (Modaflow powder III (Modaf
low Powder III), Monsanto) and defoamer benzoin (Uraflow-B), GCA Chemical Corporation (G
CA Chemical Corporation)) was also incorporated into the coating. A colored powder coating was prepared using R-960 TiO ₂ (DuPont) at a pigment / binder weight ratio of 0.7 / 1. The composition of the final powder coating is listed in Table 2.

All components were first premixed in a high speed mixer for 2 minutes to obtain a homogeneous mixture, then the solids were milled into small particles. The resulting homogeneous mixture is then continuously passed through a twin screw extruder to obtain a uniform viscous melt. The extrusion temperature was maintained at 75 ° C in zone 1 and 80 ° C in zone 2 and operated at 50 rpm. The melt extrudate was passed through a set of water cooled squeeze rolls to give a brittle product. The product was then milled using a hammer mill while slowly feeding liquid nitrogen to the milling chamber.

The powder finally obtained was grounded to a cold-rolled steel plate (Q panel (Q Panel)
) QD-36 and S-36) were electrostatically sprayed and the properties of the coatings obtained after curing at 190 ° C. for 15 minutes were evaluated. Curing was performed by placing the steel plate in a hot air oven.

[0039]

[Table 2]

Properties of Polyester Resins Carboxyl-functional polyester resins derived from PDO exhibited properties similar to NPG-based resins (Table 3). The glass transition temperature (T _g ) of the polyester decreased as the PDO component increased (FIG. 1). For example, the T _g value is NPG
The range was from 67 ° C for polyester to 55 ° C for 50% PDO polyester. The glass transition temperature of the carboxy functional polyester was 6 to 8 degrees higher than the corresponding hydroxyl functional polyester. This property of carboxylic polyesters is expected to improve the storage stability of corresponding powder coatings. T _g of the polyester, differential scanning calorimetry at a scan rate of 10 ° C. / min (
Recorded for the second heating cycle of DSC). In this second heating cycle, the sample was heated to melting and then the resin was cooled until the T _g was measured.

No crystallization or melting peaks were observed for the DSC curves of polyesters derived from NPG or NPG / PDO blends, which were found to be amorphous polyesters (FIG. 2). However, it was a polyester obtained from pure PDO, a semi-crystalline polymer with crystallization and melting temperatures of 112 ° C and 180 ° C, respectively. Therefore, partial replacement of up to 50 mol% NPG with PDO resulted in an amorphous polyester suitable for coating applications. Note that the carboxylic polyester was similar to the hydroxyl polyester with respect to its amorphous nature.

[0042]

[Table 3]

Workability After premixing, the resulting homogeneous powder mixture was continuously passed through a twin screw extruder to obtain a uniform viscous melt. Extrusion temperature at 50 rpm in zone 1 75 ° C
, Zone 2 at 80 ° C. All powder blends obtained from NPG and PDO polyesters were easy to process in the extruder (Table 4).

[0044]

[Table 4]

Storage stability The glass transition temperature of the polyester resin for powder coating should be sufficiently high for good storage stability. Commercially available polyesters for polyester / epoxy composite powder coatings have typical _Tg values of about 50-60 ° C. As expected, powder coatings formulated from carboxyl polyesters derived from up to 50% PDO showed very good storage stability due to T _g values above 55 ° C.

The storage stability test was carried out by placing the powder in a bottle, capping it, and maintaining it at 40 ° C. for 10 days. The powder was examined daily for 10 days for free flowing or lumps that did not break easily. All samples were free flowing after 10 days.

Inclined Plate Flow The inclined plate flow was measured according to the PCI standard method. It is a useful indicator of the degree of flow that occurs in the high vortex of powder coated parts. The inclined plate flow is
It is related to the zero shear melt viscosity of the base resin and is affected by the reactivity of the crosslinker and the polyester resin. At both 175 ° C and 190 ° C it was very clearly shown that increasing the PDO concentration in the PDO / NPG mixture increased the swash plate flow (Table 5). For example, pure NPG, 30% PDO, and 50% PDO had sloping plate flows of 50 mm, 68 mm, and 79 mm, respectively. Therefore, PD
The use of O improved the flow characteristics of the powder coating. Further, the higher the temperature, the faster the reaction rate, so that the powder showed a larger gradient flow at 175 ° C than at 190 ° C.

Gelation Time Reactivity Gelation time reactivity is the time required for the powder to progress to the gelled state through the liquid phase at a specified temperature. The test was performed by rubbing the powder coating on a hot plate with the tip of a wooden applicator until a solid gel was formed. The gelling time of polyester powder coating is 18 according to the method of PCI standard.
It was measured at 0 ° C. As seen in Table 5, all coatings gave similar gel times, which is consistent with the DSC test results.

[0049]

[Table 5]

Reactivity of the powder The reactivity of the carboxyl functional polyester polymer and the epoxy resin cross-linking agent is
It was examined by differential scanning calorimetry (DSC) at a scanning rate of 10 ° C./min. DS in Figure 3
From the C-curve and the test results in Table 6, it can be seen that the onset of curing exothermic peak and enthalpy are very close for each powder coating. Therefore, the NPG-based polyester and the PDO / NPG mixture-based polyester have similar reactivity to the crosslinking agent.

[0051]

[Table 6]

Impact Resistance The front and back impact resistance of the powder coating was evaluated according to the method of ASTM D2794 standard. The results in Table 7 show that PDO significantly improved flexibility in both the polyester / epoxy composite transparent powder coating and the pigmented powder coating. For example, the impact resistance of a coating thickness of about 0.064 mm (2.5 mils) is 5.65 for a coating based on pure NPG polyester.
/3.39m ・ N (50/30 inch ・ pound) (front / back), 30% P
Polyester derived from DO 11.30 / 7.91 mN (100/70
Inch-pound), and 78.0 of polyester derived from 50% PDO
It increased to 8 / 18.08 mN (160/160 inch-pounds). Furthermore, the impact resistance was strongly influenced by the thickness of the coating film, and the thicker the coating, the lower the flexibility.

[0053]

[Table 7]

Gloss Polyester / epoxy transparent and pigmented powder coatings 20 ° and 60
° Gloss is shown in FIG. The use of PDO gave slightly better gloss than pure NPG for clear coatings. 30% PDO and 1
Pigmented coatings containing polyester with 00% NPG showed similar gloss.

Hardness, Adhesion, and MEK Double Friction Resistance All coatings evaluated showed excellent adhesion to cold rolled steel substrate (Table 8). They passed the crosshatch tape adhesion test according to ASTM D-3359-92 with a value of B and no fracture was observed. NPG to PDO
There was little effect on the final pencil hardness by replacing with. MEK
For double rub resistance, 50% PDO was slightly lower than 30% PDO and pure NPG. Therefore, the coating based on PDO / NPG mixture combined good film hardness, impact flexibility with high gloss, and excellent adhesion.

[0056]

[Table 8]

Chemical and Stain Resistance Coatings exposed to 10% HCl, 10% NaOH, gasoline, and mustard for 24 hours showed excellent resistance to acids and corrosives compared to control samples. . Gasoline has a very small impact after 24 hours exposure. All coatings showed very good stain resistance to mustard. It is clear that stain resistance is related not only to chemical resistance but also to coating hardness. Soft resins are easier to stain than hard resins. The coatings derived from PDO had little effect on pencil hardness and chemical resistance and therefore no noticeable effect on stain resistance (Table 9). Data are presented in the form of grades from 10 with no effect to 1 with the most severe degradation.

[0058]

[Table 9]

Flexible-Conical Mandrel Bending Test and T-Bending Test The conical mandrel bending test is a cylindrical mandrel tester (Gardner Laboratory, Inc.) with a diameter of 3.2 mm (
1/8 inch)) for 3 seconds by bending the coated panel.
The test results are summarized in Table 10. All clear coated panels passed the test, i.e. no cracks were seen. However, the pigmented coating formulated using pure NPG polyester cracked at about 6 mm in the mandrel bending test,
On the other hand, a coating using a polyester derived from 30% PDO passed the test.

The flexibility measured by the T-bend test gave a coating of 1T by using 30% PDO, whereas pure NPG gave a value of 3T. 50%
The coating using PDO gave very good flexibility with a value of 0T. For the pigmented coating, pure NPG gave a value of 5T, comparable to 3T with 30% PDO. Therefore, these results are
The data further demonstrate that the DO contribution contributes to improving the flexibility of the powder coating.

[0061]

[Table 10]

[Brief description of drawings]

[Figure 1]   3 is a graph showing the glass transition temperature of various formulations.

FIG. 2 is a graph showing a differential scanning calorimetry (DSC) curve of a carboxypolyester resin.

FIG. 3 is a graph showing a polyester / epoxy composite powder coating differential scanning calorimetry (DSC) curve.

FIG. 4 is a graph showing the gloss of clear and colored polyester / epoxy powder coatings.

[Procedure for Amendment] Submission for translation of Article 34 Amendment of Patent Cooperation Treaty

[Submission date] July 24, 2002 (2002.7.24)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Contents of correction]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Contents of correction]

(Summary of the Invention) From the above, the present invention comprises: a) one or more kinds of aliphatic glycols and one or more kinds of polycarboxylic acids and / or
Alternatively, an anhydride is reacted in the presence of an esterification catalyst, and a polyester resin obtained by endcapping the obtained polyester with an endcapping agent so that the polyester has a carboxyl chain end, and b) an epoxy resin crosslinker, Obtained by reacting, the aliphatic glycol is 5 to 90% on a molar basis.
1,3-propanediol, polyester resin is 30 to 120mgK
A polyester powder coating composition having an acid number of OH / g is included.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Contents of correction]

According to the invention: a) a mixture of neopentyl glycol and 1,3-propanediol (1,3-
Propanediol constitutes 5 to 90% of the mixture on a molar basis) and a mixture of terephthalic acid and isophthalic acid (the ratio of terephthalic acid to isophthalic acid is 90/10).
To 50/50) in the presence of dibutyltin oxide, and end-capping by adding trimellitic anhydride to obtain a polyester resin (polyester resin having an acid value of 30 to 120 mgKOH / g). A), and b) an epoxy resin cross-link which is a diglycidyl ether of 2,2-bis (4-hydroxyphenyl) propane, which has been previously reacted with bisphenol A and has a molecular weight of 450 to 900 per epoxy. Provided is a polyester powder coating composition obtained by reacting an agent with.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Contents of correction]

The preferred carboxyl-capped polyester has an acid value of preferably 40 to 1
It is 10 mgKOH / g, and has a property that T _g is higher than 40 ° C.
Acid value = 56,100 / equivalent (56,100 is the weight (unit: mg) per mol of KOH). When the equivalent weight is low and the acid value is high, the crosslink density is high and brittle, and when the equivalent weight is high or the acid value is low, the crosslink density is low, and thus performances such as resistance to methyl ethyl ketone and a solvent are deteriorated. The above T _g range is generally necessary to obtain good storage stability.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW (72) Inventor Chiyo, Leachyan             United States, New Jersey             08512, Cranberry, Princeton A             Mum 184 (72) Thomas Clayton, Inventor Fous Juhner             Riz, Texas 77469, United States             Timmond, Utdland Drive 2211 (72) Inventor Boone, Wyndham Henry             United States, Ohio 44720, No             Su Canton, Baylor Circle 2446 F-term (reference) 4J038 DB062 DB072 DB132 DD041                       DD061 DD071 DD081 DD241                       GA06 KA03 MA02 MA14 NA11

Claims (10)

[Claims] 1. A polyester powder coating composition comprising: a) one or more aliphatic glycols and one or more polycarboxylic acids and / or
Or a polyester resin obtained by reacting an anhydride with an esterification catalyst, wherein the polyester is end-capped with an end capping agent so that the polyester has a carboxyl chain end; and b) Obtained by reacting with an epoxy resin cross-linking agent, wherein the aliphatic glycol is 5 to 9 on a molar basis.
The composition comprising 0% 1,3-propanediol. 2. The 1,3-propanediol is one of the aliphatic glycols.
The powder coating composition according to claim 1, comprising 0 to 50%. 3. The powder coating composition according to claim 1 or 2, wherein the aliphatic glycol has a number average molecular weight of 62 to 500. 4. The aliphatic glycol is 1,3-butylene glycol, 1
, 4-butylene glycol, ethylene glycol, diethylene glycol, 1,
2-propanediol, 1,6-hexanediol, triethylene glycol,
Group consisting of tetraethylene glycol, tripropylene glycol, tetrapropylene glycol, dipropylene glycol, 2-methyl-1,3-propanediol, polycarbonate diol with a hydroxyl number of 56 to 168, dimeric fatty alcohol, and neopentyl glycol. Claim 1, 2 selected from
Or the powder coating composition according to the item 3. 5. The powder coating composition according to claim 4, wherein the aliphatic glycol is neopentyl glycol. 6. A powder coating composition according to any one of the preceding claims further comprising a small amount of branching agent selected from the group consisting of trimethylolpropane, trimethylolethane and pentaerythritol. 7. Any of the preceding claims, wherein said polycarboxylic acid and / or anhydride is selected from the group consisting of saturated, unsaturated, aliphatic and aromatic polycarboxylic acids and / or anhydrides. The powder coating composition according to item 1. 8. Phthalic acid, isophthalic acid, terephthalic acid, sebacic acid, maleic acid, fumaric acid, succinic acid, adipic acid, azelaic acid, malonic acid, dodecanedioic acid, trimellitic acid, pyromellitic acid, and their anhydrides. The powder coating composition according to claim 7, which contains a polycarboxylic acid and / or an anhydride selected from the group consisting of a compound, or a mixture thereof. 9. A polycarboxylic acid and / or anhydride as claimed in claim 8 containing a polycarboxylic acid and / or anhydride selected from the group consisting of isophthalic acid, terephthalic acid and trimellitic acid and their anhydrides or mixtures thereof. Powder coating composition. 10. A polyester powder coating composition comprising: a) a mixture of neopentyl glycol and 1,3-propanediol (wherein 1,
3-propanediol constitutes 5 to 90% of the mixture on a molar basis),
A mixture of terephthalic acid and isophthalic acid (the ratio of terephthalic acid and isophthalic acid is 9
It is in the range of 0/10 to 50/50) in the presence of dibutyltin oxide, and the polyester resin obtained by endcapping by adding trimellitic anhydride, and b) preliminarily reacting with bisphenol A The composition obtained by reacting with an epoxy resin cross-linking agent which is a diglycidyl ether of 2,2-bis (4-hydroxyphenyl) propane having a molecular weight of 450 to 900 per epoxy.