JPWO2018084062A1 - Polyester polyol resin and paint - Google Patents

Abstract

To provide a polyester polyol resin having high solubility in a weak solvent and excellent balance between hardness and flexibility in a cured coating film, a curable resin composition, a paint and a coated steel sheet using the same. A polyester polyol resin having a weight average molecular weight (Mw) in the range of 3,000 to 120,000, wherein the following (A) to (C) and (D1) or (D2) are essential reaction raw materials. A polyester polyol resin characterized by that. C4-C12 linear aliphatic diol compound (A) Aliphatic diol compound having branched structure in molecular structure (B) Aliphatic dicarboxylic acid compound or derivative thereof (C) Trifunctional or higher functional polyol compound (C) D1) Trifunctional or higher functional polycarboxylic acid compound or derivative thereof (D2)

Description

  The present invention relates to a polyester polyol resin which has high solubility in a weak solvent and is excellent in the balance between hardness and flexibility in a cured coating film, a curable resin composition using the same, a paint, and a coated steel plate.

  As a coating method of various metal parts or metal molded products such as home appliances, automobile parts, building materials, can making, etc., a pre-coating method in which a steel plate is previously coated and a post-coating method in which a steel plate is molded after being formed are known. The steel plate used in the precoating method is generally called precoated metal (hereinafter sometimes abbreviated as "PCM"), and the steel plate coated in advance is cut in accordance with the application and formed into various shapes for use. In addition to the hardness and gloss of the coating film surface, the PCM coating is required to have extremely high flexibility and adhesion to steel plates. Further, from the viewpoint of improving the painting work environment, it is also important that the solubility in a solvent having a low environmental impact, which is generally called weak solvent, is high, and the storage stability of the weak solvent solution. As the PCM paint, paints of various forms such as two-component curing type, UV curing type and volatilization drying type are used, and the resin system is also various as polyester resin, fluorine resin, acrylic resin, etc. Among them, a two-component curable paint having a polyester resin as a main ingredient is widely used.

  As a two-component curing type PCM coating containing a polyester resin as a main component, for example, terephthalic acid, isophthalic acid, 2-methyl-1,3-propanediol, number average molecular weight using 1,6-hexanediol as a reaction raw material Coatings based on a polyester resin having a Mn of 11,000 are known (see Patent Document 1). However, the polyester resin described in Patent Document 1 has low solubility in weak solvents and has a surface hardness in a cured coating film. The balance between performance and flexibility was not enough.

JP-A-9-12969

  Therefore, the problem to be solved by the present invention is polyester polyol resin having high solubility in weak solvent and excellent balance of hardness and flexibility in a cured coating film, curable resin composition using the same, paint, and It is in providing a coated steel plate.

  As a result of intensive studies to solve the above problems, the inventors of the present invention have studied straight-chain aliphatic diol compounds having 4 to 12 carbon atoms, aliphatic diol compounds having a branched structure in their molecular structure, and aliphatic dicarboxylic acids. The polyester polyol resin having the compound and the polyol compound of trifunctional or higher functional or the polycarboxylic acid compound of trifunctional or higher as the essential reaction raw material has high solubility in the weak solvent, and balance of hardness and flexibility in the cured coating film It has been found that the present invention is excellent.

That is, the present invention is a polyester polyol resin having a weight average molecular weight (Mw) in the range of 3,000 to 120,000, and the following (A) to (C) and (D1) or (D2): The present invention relates to a polyester polyol resin characterized by being used as an essential reaction material.
Straight-chain aliphatic diol compound having 4 to 12 carbon atoms (A)
Aliphatic diol compounds having a branched structure in the molecular structure (B)
Aliphatic dicarboxylic acid compound or derivative thereof (C)
Trifunctional or higher functional polyol compound (D1)
Trifunctional or higher functional polycarboxylic acid compound or derivative thereof (D2)

  The present invention further relates to a curable resin composition comprising a main agent containing the polyester polyol resin and a curing agent.

  The present invention further relates to a paint comprising the curable resin composition.

  The present invention further relates to a coated steel sheet having a coating film comprising the above-mentioned paint.

  According to the present invention, it is possible to provide a polyester polyol resin which has high solubility in a weak solvent and is excellent in the balance between hardness and flexibility in a cured coating, and a curable resin composition, a paint and a coated steel plate using the same. Can.

The polyester polyol resin of the present invention has a weight-average molecular weight (Mw) in the range of 3,000 to 120,000, and the following reaction materials (A) to (C) and (D1) or (D2) as essential reaction raw materials It is characterized by
Straight-chain aliphatic diol compound having 4 to 12 carbon atoms (A)
Aliphatic diol compounds having a branched structure in the molecular structure (B)
Aliphatic dicarboxylic acid compound or derivative thereof (C)
Trifunctional or higher functional polyol compound (D1)
Trifunctional or higher functional polycarboxylic acid compound or derivative thereof (D2)

  Specifically, the linear aliphatic diol compound (A) having 4 to 12 carbon atoms is 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, or 1,12-dodecanediol. These may be used alone or in combination of two or more. Among them, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-, in that they are excellent in the balance between hardness and flexibility in the cured coating film. Either octanediol is preferred, and 1,4-butanediol or 1,6-hexanediol is more preferred.

  If the aliphatic diol compound (B) having a branched structure in the molecular structure is a diol compound of an aliphatic hydrocarbon having a branched chain, the number and molecular weight of the branched chain are not particularly limited, and any compound may be used. It is good. Specifically, 2-methyl-1,3-propanediol, neopentyl glycol, 2-ethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2-ethyl-2-methyl- 1,3-propanediol, 2-ethylbutane-14-butanediol, 2,3-dimethyl-1,4-butanediol, 3-methyl-1,5-pentanediol, 2,4-dimethyl-1,5- Pentanediol, 3,3-dimethylpentane-1,5-diol, 2,2-diethyl-1,3-propanediol, 3-propylpentane-1,5-diol, 2,2-diethyl-1,4-diol Butanediol, 2,4-diethyl-1,5-pentanediol, 2,2-dipropyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanedio Le, 2,5-diethyl-1,6-hexanediol, and the like. The aliphatic diol compounds (B) having a branched structure in the molecular structure may be used alone or in combination of two or more. Among them, a compound having a carbon atom number of 4 to 6 is preferable, and 2-methyl-1,3-propanediol is more preferable, from the point of being excellent in the balance between hardness and flexibility in the cured coating film.

  The polyester polyol resin of the present invention is a diol compound other than the straight-chain aliphatic diol compound (A) having 4 to 12 carbon atoms and the aliphatic diol compound (B) having a branched structure in the molecular structure. May be used as part of the reaction raw material. Other diol compounds include, for example, straight-chain aliphatic diol compounds having 1 to 3 or 13 or more carbon atoms; alicyclic structure-containing diol compounds such as cyclohexanediol and cyclohexanedialcohol; and aromatic rings such as biphenol and bisphenol Diol compounds; polyether diols; polycarbonate diols etc. may be mentioned.

  The polyester polyol resin of the present invention is excellent in the balance between hardness and flexibility in a cured coating film and sufficiently exerts the effect of high solubility in a weak solvent. The total mass of the linear aliphatic diol compound (A) having 4 to 12 carbon atoms and the aliphatic diol compound (B) having a branched structure in the molecular structure is preferably 60% by mass or more, 90 It is more preferable that it is mass% or more. Further, the ratio of the linear aliphatic diol compound (A) having 4 to 12 carbon atoms to the total mass of the diol raw material is preferably in the range of 3 to 30% by mass, and in the range of 5 to 20% by mass Is preferred. The proportion of the aliphatic diol compound (B) having a branched structure in the molecular structure with respect to the total mass of the diol raw material is preferably in the range of 50 to 97 mass%, and more preferably 70 to 95 mass%. . Furthermore, the mass ratio [(A) / (B)] of the linear aliphatic diol compound (A) having 4 to 12 carbon atoms and the aliphatic diol compound (B) having a branched structure in the molecular structure Is preferably in the range of 3/97 to 30/70.

  Examples of the aliphatic dicarboxylic acid compound or its derivative (C) include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and the like These acid anhydrides and acid halides may be mentioned. The aliphatic dicarboxylic acid compounds or their derivatives (C) may be used alone or in combination of two or more. Among them, a linear saturated aliphatic dicarboxylic acid compound having 4 to 8 carbon atoms or a derivative thereof is preferable in that it is excellent in the balance between the hardness and the flexibility in a cured coating film.

  In the polyester polyol resin of the present invention, in addition to the aliphatic dicarboxylic acid compound or its derivative (C), another dicarboxylic acid compound or its derivative may be used as part of the reaction raw material. Other dicarboxylic acid compounds or derivatives thereof include, for example, phthalic acid, isophthalic acid, terephthalic acid, and aromatic dicarboxylic acid compounds such as acid anhydrides and acid halides thereof or derivatives thereof (C '); hexahydrophthalic acid And tetrahydrophthalic acid, methyltetrahydrophthalic acid, and alicyclic dicarboxylic acid compounds such as acid anhydrides and acid halides or derivatives thereof (C ′ ′), etc. Among them, hardness and flexibility in a cured coating film It is preferable to use an aromatic dicarboxylic acid compound or its derivative (C ') from the point of being excellent in balance with the above.

  The polyester polyol resin of the present invention is excellent in the balance between hardness and flexibility in a cured coating film and sufficiently exerts the effect of high solubility in a weak solvent, so relative to the total mass of the dicarboxylic acid raw material, It is preferable to use 1 mass% or more of the said aliphatic dicarboxylic acid compound or its derivative (C), and it is more preferable to use it in the ratio of 3-30 mass%. Moreover, it is preferable that the total mass of the said aliphatic dicarboxylic acid compound or its derivative (C) and an aromatic dicarboxylic acid compound or its derivative (C ') is 60 mass% or more with respect to the total mass of the dicarboxylic acid raw material And 90% by mass or more. Furthermore, the mass ratio [(C) / (C ′)] of the aliphatic dicarboxylic acid compound or the derivative (C) thereof to the aromatic dicarboxylic acid compound or the derivative (C ′) thereof is 3/97 to 30/70. It is preferable to be in the range of

  As long as the trifunctional or higher functional polyol compound (D1) is a compound having three or more hydroxyl groups in one molecule, the other specific structure is not particularly limited, and a wide variety of compounds can be used. Specific examples of the trifunctional or higher functional polyol compound (D1) include, for example, aliphatic polyol compounds such as trimethylolethane, trimethylolpropane, glycerin, hexanetriol and pentaerythritol; and aromatic polyol compounds such as trihydroxybenzene; Obtained by ring-opening polymerization of the aliphatic polyol compound or aromatic polyol compound with a cyclic ether compound such as ethylene oxide, propylene oxide, tetrahydrofuran, ethyl glycidyl ether, propyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether and the like Polyether modified polyol compounds and the like. The trifunctional or higher functional polyol compound (D1) may be used alone or in combination of two or more. Among them, it is preferable to use an aliphatic polyol compound, and it is more preferable to use a trifunctional aliphatic polyol compound, from the point of being excellent in the balance between hardness and flexibility in a cured coating film.

  The specific structure is not particularly limited as long as the trifunctional or higher functional polycarboxylic acid compound or its derivative (D2) is a compound having three or more carboxy groups in one molecule, and a wide variety of compounds may be used. Can. Specific examples of the trifunctional or higher functional polycarboxylic acid compound or its derivative (D2) include aliphatic polycarboxylic acid compounds such as 1,2,5-hexanetricarboxylic acid and 1,2,4-cyclohexanetricarboxylic acid. And acid anhydrides and acid halides thereof; aromatic polycarboxylic acid compounds such as trimellitic acid, trimellitic anhydride, 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, and the like An acid anhydride, an acid halide, etc. are mentioned. These may be used alone or in combination of two or more.

  In the polyester polyol resin of the present invention, the trifunctional or higher functional polyol compound (D1) and the trifunctional or higher functional polycarboxylic acid compound or its derivative (D2) are components used to introduce a branched structure into a resin structure. And both can be used equally. Among them, the trifunctional or higher functional polyol compound (D1) is more preferable in terms of availability and reactivity. The polyester polyol resin of the present invention has a high solubility in a weak solvent, and the effect of being excellent in the balance between the hardness and the flexibility in a cured coating film is sufficiently exhibited. It is preferable to use the trifunctional or higher polyol compound (D1) or the trifunctional or higher polycarboxylic acid compound or its derivative (D2) in the range of 0.05 to 15% by mass, and the range of 0.1 to 10% by mass It is more preferable to use

  The method for producing the polyester polyol resin of the present invention is not particularly limited, and may be produced by any method. Specifically, all of the reaction materials may be reacted at one time, or a method in which a part of the reaction materials is added in a divided manner, or after reacting the components (A) to (C), (D1) or The component (D2) may be added and reacted stepwise. The reaction temperature is preferably about 180 to 300 ° C. like the reaction temperature of a general polyester resin, and if necessary, a known conventional esterification catalyst may be used.

  The polyester polyol resin of the present invention may be reacted in an organic solvent, if necessary, or an organic solvent may be added after completion of the reaction to adjust the viscosity and the like. The organic solvent is not particularly limited as long as it can dissolve the polyester polyol resin, and known organic solvents can be used. In particular, the polyester polyol resin of the present invention also has high solubility in organic solvents of the type generally called weak solvents. As an organic solvent generally called a weak solvent, for example, Yamaichi Chemical Industry Co., Ltd. “Nafsa No. 6”, JX Nippon Oil & Energy Co., Ltd. “Mineral Spirit”, JX Nippon Oil & Energy Co., Ltd. “A Solvent And “Sorbesso 100” and “Sorbesso 150” manufactured by Exxon Mobil Co., Ltd. and the like. These may be used alone or in combination of two or more.

  In addition, as an organic solvent with high solubility of the polyester polyol resin of the present invention, for example, alkylene glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether Monoalkyl ethers; dialkylene glycol dialkyl ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate etc Ruki glycol alkyl ether acetate: toluene, aromatic hydrocarbons such as xylene and the like. These may be used alone or in combination of two or more.

  Although the dilution rate by these organic solvents is suitably adjusted according to a use etc., for example, when using the said polyester polyol resin for a coating use, it is preferable to dilute to such an extent that a non volatile matter will be 40-80 mass%. . Moreover, it is preferable to use 70 mass% or more of weak solvents among the organic solvents to be used, and it is more preferable to use 90 mass% or more.

  The weight average molecular weight (Mw) of the polyester polyol resin of the present invention is preferably in the range of 3,000 to 120,000, from the viewpoint of being excellent in the balance between the hardness and the flexibility in the cured coating film. More preferably, it is in the range of 50,000. The number average molecular weight (Mn) is preferably in the range of 2,000 to 10,000, and more preferably in the range of 2,500 to 6,000. The molecular weight distribution (Mw) / (Mn) is preferably in the range of 1.2 to 20, and more preferably in the range of 1.5 to 6. In the present invention, the molecular weight of the polyester polyol resin is a value measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device; Tosoh Co., Ltd. HLC-8320 GPC
Column; Tosoh Corp. TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel 1000HXL
Detector; RI (differential refractometer)
Data processing; Tosoh Corp. multi station GPC-8020 model II Measurement conditions; Column temperature 40 ° C
Solvent Tetrahydrofuran
Flow rate 0.35 ml / min Standard; monodispersed polystyrene sample; 0.2% tetrahydrofuran solution in terms of resin solid content filtered with a microfilter (100 μl)

  The hydroxyl value of the polyester polyol resin of the present invention is preferably in the range of 2 to 100 mg KOH / g, and more preferably 20 to 70 mg KOH / g, since it becomes a resin having excellent curability. Moreover, it is preferable that the acid value of the polyester polyol resin of this invention is 10 mgKOH / g or less.

  The curable resin composition of the present invention comprises a main agent containing the polyester polyol resin and a curing agent.

  The main agent may contain other resins other than the polyester polyol resin of the present invention. As other resin, other polyol resin other than the polyester polyol resin of this invention, etc. are mentioned. When these other resins are used, the effect of the excellent balance of hardness and flexibility in the cured coating film exhibited by the present invention and high solubility in a weak solvent is sufficiently exhibited, so the main agent is contained. It is preferable to use 50 mass% or more of the polyester polyol resin of the said this invention with respect to the total mass of the resin component to be used, and it is preferable to use 80 mass% or more.

  The curing agent only needs to contain a component capable of causing a curing reaction with the polyester polyol resin of the present invention, and such components include, for example, amino resin, polyisocyanate resin, resole resin, epoxy resin, etc. It can be mentioned. These may be used alone or in combination of two or more. The components of the curing agent are appropriately selected according to the application and use environment of the curable resin composition, desired physical properties of the cured product, etc., but any curing agent is used as long as the polyester polyol resin of the present invention is used as the main agent. Even in the case, the effect of excellent balance of the hardness and the flexibility in the cured coating film exhibited by the present invention is sufficiently exhibited.

  Specific examples of the amino resin include, for example, methylolated amino resin synthesized from at least one of melamine, urea and benzoguanamine and formaldehydes; a part or all of the methylol group of the methylolated amino resin is methanol, Those obtained by alkyl etherification with lower monohydric alcohols such as ethanol, propanol, isopropanol, butanol and isobutanol can be mentioned.

  Examples of such amino resin products include, for example, “Cymel 303” (methylated melamine resin), “Cymel 350” (methylated melamine resin) manufactured by Allnex Co., “Yuban 520” manufactured by Mitsui Chemicals, Inc. n-Butylated Modified Melamine Resin), “U-Ban 20-SE-60” (n-Butylated Modified Melamine Resin), “U-Ban 2021” (n-Butylated Modified Melamine Resin), “U-Bon 220” (n-Butylated Modified melamine resin), "U-Bane 22R" (n-butylated modified melamine resin), "U-Ban 2028" (n-butylated modified melamine resin), "U-Bang 165" (isobutylated modified melamine resin), "U-Bang 114" (n-butylated modified melamine resin) Isobutylated modified melamine resin), "Yuban 62" (isobutylated modified melamine resin), "Yuban 60R "(isobutylated modified melamine resin) and the like. When using these amino resins, you may add acid compounds, such as phosphoric acid ester, as a hardening accelerator.

  Specific examples of the polyisocyanate resin include, for example, aliphatic diisocyanate compounds such as butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate; norbornane diisocyanate, Alicyclic diisocyanate compounds such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate; Aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, tetramethyl xylylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate A polymethylene poly having a repeating structure represented by the following structural formula (1) E sulfonyl polyisocyanates; these isocyanurate modified product, a biuret modified product, an allophanate modified product, and a blocked polyisocyanate resin or the like.

［式中、Ｒ^１はそれぞれ独立に水素原子、炭素原子数１〜６の炭化水素基の何れかである。Ｒ^２はそれぞれ独立に炭素原子数１〜４のアルキル基、又は構造式（１）で表される構造部位と＊印が付されたメチレン基を介して連結する結合点の何れかである。ｍは０又は１〜３の整数であり、ｌは１以上の整数である。］

[In formula, R < ¹ > is respectively independently a hydrogen atom and either a C1-C6 hydrocarbon group. R ² each independently represents an alkyl group having 1 to 4 carbon atoms, or a bonding point which is connected to the structural portion represented by Structural Formula (1) via a methylene group marked with an asterisk (*). m is an integer of 0 or 1 to 3, and l is an integer of 1 or more. ]

  As a specific example of the said epoxy resin, the polyglycidyl ether of a polyol compound, the polyglycidyl ester of a polycarboxylic acid compound, a bisphenol-type epoxy resin, a novolak-type epoxy resin etc. are mentioned, for example.

  The curable resin composition of the present invention comprises a curing catalyst, a curing accelerator, a pigment, a pigment dispersant, a matting agent, a leveling agent, a drying inhibitor, an ultraviolet absorber, an antifoaming agent, a thickener, an anti-settling agent, An organic solvent or the like may be added. The compounding ratio of each of these components and the kind of compound are suitably adjusted by the use and desired performance of a curable resin composition. The curable resin composition of the present invention may be a one-part type or a two-part type. When the curable resin composition of the present invention is a two-component type, the various additives can be added to either or both of the main agent and the curing agent.

  The application of the curable resin composition of the present invention is not particularly limited, but it can be preferably used for paints and adhesives since it is excellent in the balance of hardness and flexibility in a cured coating film, and is particularly suitable as a paint for coated steel sheet It can be used for The coated steel sheet of the present invention can be used, for example, in various metal parts such as home appliances and automobile parts, building materials, precoated metals for metal molded products, cans and the like.

  When the paint of the present invention is used for a coated steel sheet, the coating may be either a single layer or multiple layers. In the case of multiple layers, one or more of the paints of the present invention may be applied one on top of the other, or the paint of the present invention may be combined with another paint. Other paints include, for example, paints mainly composed of polyester resin, urethane resin, epoxy resin and the like. In general, a method of applying a layer called a primer layer on a steel plate and then applying a layer called a top coat layer is widely used for coating a steel plate. The paint of the present invention can be used as a primer layer or a top coat layer. The thickness of the primer layer is preferably about 0.5 to 30 μm. The thickness of the topcoat layer is preferably about 1 to 60 μm. The coating method may be any known conventional method such as spray coating, dip coating, spin coating, flow coating, roller coating and the like. The curing conditions of the coating are appropriately adjusted depending on the selection of the curing agent, film thickness and the like, but a method of heat curing in a temperature range of about 120 to 350 ° C. for several seconds to several minutes is preferable.

  Hereinafter, the present invention will be described in more detail by way of specific synthesis examples and examples. Hereinafter, "parts" and "%" are based on mass unless otherwise specified.

  The number average molecular weight (Mn), the weight average molecular weight (Mw), and the molecular weight distribution (Mw / Mn) in Examples of the present application were measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device; Tosoh Co., Ltd. HLC-8320 GPC
Column; Tosoh Corp. TSKgel 4000HXL, TSKgel 3000HXL, TSKgel 2000HXL, TSKgel 1000HXL
Detector; RI (differential refractometer)
Data processing; Tosoh Corp. multi station GPC-8020 model II Measurement conditions; Column temperature 40 ° C
Solvent Tetrahydrofuran
Flow rate 0.35 ml / min Standard; monodispersed polystyrene sample; 0.2% tetrahydrofuran solution in terms of resin solid content filtered with a microfilter (100 μl)

Example 1 Production of polyester polyol resin (1) solution In a reaction vessel equipped with a stirrer, a condenser and a thermometer, 1188.6 parts by mass of 2-methyl-1,3-propanediol, 150 parts by mass of 1,6-hexanediol 10 parts by mass of trimethylolpropane, 2000 parts by mass of isophthalic acid, 220 parts by mass of adipic acid, and 3.53 parts by mass of a titanium phosphate catalyst (“Orgatics TC-1040” manufactured by Matsumoto Fine Chemical Co., Ltd.). The reaction is carried out at 200 to 250 ° C. for 18 hours while stirring under a nitrogen stream, and the number average molecular weight (Mn) 3,700, weight average molecular weight (Mw) 8,400, acid value 5.6 mg KOH / g, hydroxyl value 26 mg KOH / g of polyester polyol resin (1) was obtained. The polyester polyol resin (1) thus obtained is dissolved in a mixed solvent of 900 parts by mass of "Solvesso 100" manufactured by Exxon Mobil Limited and 300 parts by mass of propylene glycol monomethyl ether acetate to give a polyester polyol having a nonvolatile content of 68.4% by mass. Resin (1) solution was obtained. The Gardner viscosity of the polyester polyol resin (1) solution was Z2-Z3.

Example 2 Production of polyester polyol resin (2) solution In a reaction vessel equipped with a stirrer, a condenser and a thermometer, 1081.5 parts by mass of 2-methyl-1,3-propanediol, 150 parts by mass of 1,6-hexanediol 165 parts by mass of trimethylolpropane, 1855 parts by mass of isophthalic acid, 350 parts by mass of adipic acid, and 3.57 parts by mass of a titanium phosphate catalyst (“Orgatics TC-1040” manufactured by Matsumoto Fine Chemical Co., Ltd.). The reaction is carried out at 200 to 250 ° C. for 13 hours while stirring under a nitrogen stream, and the number average molecular weight (Mn) 4,300, weight average molecular weight (Mw) 16,400, acid value 6.8 mg KOH / g, hydroxyl value 46 mg KOH / g of polyester polyol resin (2) was obtained. The obtained polyester polyol resin (2) was dissolved in 1264.3 parts by mass of "Solvesso 100" manufactured by Exxon Mobil Limited to obtain a polyester polyol resin (2) solution having a nonvolatile content of 69.5% by mass. The Gardner viscosity of the polyester polyol resin (2) solution was Z3-Z4.

Comparative Example 1 Production of polyester polyol resin (1 ′) solution In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, 453.2 parts by mass of neopentyl glycol, 440.0 parts by mass of 1,6-hexanediol, trimethylolpropane 190.0 parts by mass, 464.4 parts by mass of phthalic anhydride, 1215.3 parts by mass of isophthalic acid, and 464.4 parts by mass of glycidyl ester of neodecanoic acid were charged. It is made to react at 180-250 ° C for 13 hours while stirring under nitrogen stream, and polyester polyol resin (1 ') having a weight average molecular weight (Mw) of 12,000, an acid value of 8.5 mg KOH / g and a hydroxyl value of 52 mg KOH / g. Obtained. The obtained polyester polyol resin (1 ') is dissolved in a mixed solvent of 1364.4 parts by mass of "Solvesso 100" manufactured by Exxon Mobil Limited and 151.8 parts by mass of propylene glycol monomethyl ether acetate, and the non-volatile content 65.0 The polyester polyol resin (1 ') solution of mass% was obtained. The Gardner viscosity of the polyester polyol resin (1 ') solution was Z-Z1.

Solubility Test in Weak Solvent The polyester polyol resin solutions obtained in Examples 1 and 2 and Comparative Example 1 were stored under the conditions of room temperature 25 ° C., and the state after one month was visually evaluated.
Polyester polyol resin (1) solution: No clouding was observed at all, and the flowability was also good.
Polyester polyol resin (2) solution: No white turbidity was observed, and the fluidity was also good.
No polyester polyol resin (1 ') clouding was observed at all, and the flowability was also good.

Example 3 Production of Coating (1) 69 parts by mass of polyester polyol resin (1) solution, 94.5 parts by mass of titanium oxide, 0.9 parts by mass of silica, 40.9 parts by mass of mixed solvent are mixed, Particle size of titanium oxide Dispersion was carried out with a paint shaker until the particle size became 10 μm or less. Then, 69 parts by mass of polyester polyol resin (1) solution, 16.7 parts by mass of amino resin, 0.9 parts by mass of curing accelerator, 0.9 parts by mass of matting agent, 1.5 parts by mass of leveling agent, mixed solvent 7 2 parts by mass were added and mixed, and the mixture was further adjusted with a mixed solvent so that the Ford cup # 4 viscosity at 25 ° C. became about 100 seconds, to obtain a paint (1).

Example 4 Production of Paint (2) In Example 3, 69 parts by mass of the polyester polyol resin (1) solution was changed to 68 parts by mass of the polyester polyol resin (2) solution, and the mixed solvent amount at the time of dispersion was 40.9 parts A paint (2) was obtained in the same manner as in Example 3 except that the content was changed to 52.6 parts by mass.

Comparative Example 2 Production of Paint (1 ′) In Example 3, 69 parts by mass of the polyester polyol resin (1) solution was changed to 73 parts by mass of the polyester polyol resin (1 ′) solution, and the mixed solvent amount at the time of dispersion was 40. A paint (1 ') was obtained in the same manner as in Example 3 except that the amount was changed from 9 parts by mass to 33.3 parts by mass.

Production Example 1 Production of Primer Coating 78.8 parts by mass of alkyd resin, 21.1 parts by mass of calcium phosphate, 62.3 parts by mass of titanium oxide, 0.9 parts by mass of silica, and 25.1 parts by mass of mixed solvent are mixed to obtain titanium oxide Dispersion was carried out with a paint shaker until the particle size of the powder became 10 μm or less. Next, 78.8 parts by mass of alkyd resin, 16.7 parts by mass of amino resin, 0.9 parts by mass of curing accelerator, 0.9 parts by mass of matting agent, and 4.4 parts by mass of mixed solvent are added and mixed, and further The mixture was adjusted with a mixed solvent so that the Ford cup # 4 viscosity at 25 ° C. became about 100 seconds, to obtain a primer paint.

Details of each compounding component used in production of paint and primer paint are as follows: "Ti-PureR 960" manufactured by Dupont
Silica: Evonik Industries "Aerosil R972"
Mixed solvent: A mixture of "Solvesso 100" manufactured by Exxon Mobil Co., Ltd. and propylene glycol monomethyl ether acetate at a mass ratio of 7: 3. Amino resin: "Cymel 303" manufactured by Allnex Co.
Hardening accelerator: "Cycat 4040" (sulfonic acid type) manufactured by Allnex Co.
Matting agent: "Syloid ED3" (silica type) manufactured by Allnex
Leveling agent: Allex "Modaflow 2100":
Alkyd resin: "Beckolite 46-118" manufactured by DIC Corporation
Calcium phosphate: "Halox 430" manufactured by ICL / Advanced additives

Examples 5 and 6 and Comparative Example 3 Production and Evaluation of Coated Steel Sheet A coated steel sheet was manufactured in the following manner, and various evaluations were performed. The results are shown in Table 1.

Production of coated steel sheet The primer coating obtained above was applied to a 0.5 mm thick hot-dip galvanized chromate-treated steel sheet with a bar coater, and dried by heating in an oven at 250 ° C for 20 seconds (metal peak temperature is 199 to 204 ° C). ), A primer layer having a dry film thickness of 5 μm was formed. Next, the paint obtained above is applied by a bar coater on the primer layer, heat dried in an oven at 250 ° C. for 40 seconds (metal peak temperature is 232 to 241 ° C.), and it has a top coat layer with a dry film thickness of 15 μm. I obtained a painted steel plate.

Measurement of Gloss The 60 ° reflectance of the coated surface of the coated steel sheet obtained above was measured according to EN 13523-2 and evaluated as follows.
A: 90% or more B: less than 90%

Measurement of Pencil Hardness The pencil hardness of the coated surface of the coated steel sheet obtained above was measured according to EN 13523-4.

Evaluation of flexibility (1) Crack free test The flexibility of the coating was evaluated by the T-bend bending test. In accordance with EN 13523-7, the coated steel sheet obtained above was bent by 180 °, and a crack generated in a bent portion was observed with a 10-fold loupe. 0T is the case where the coated steel plate is bent 180 ° without inserting anything in the bent portion, and (X / 2) T is the case where X plates having the same thickness as the coated steel plate are bent in the bent portion as (X / 2) T. It evaluated by the minimum value which a crack does not generate.

Evaluation of flexibility (2) Tape test The flexibility of the coating was evaluated by the T-bend bending test. In accordance with EN 13523-7, the coated steel plate was bent by 180 °, and “Niceban's“ Cellotape ”was attached to the bent portion, and evaluation was made based on the presence or absence of peeling of the coating film when peeled off rapidly. If there is nothing in the bent part and the coated steel sheet is bent at 180 °, it is 0T, and if it is folded with X sheets of the same thickness as the coated steel sheet in the bent part, it is (X / 2) T. It evaluated by the minimum value which does not occur.

Claims (6)

A polyester polyol resin having a weight average molecular weight (Mw) in the range of 3,000 to 120,000, wherein the following (A) to (C) and (D1) or (D2) are essential reaction raw materials Polyester polyol resin characterized by
Straight-chain aliphatic diol compound having 4 to 12 carbon atoms (A)
Aliphatic diol compounds having a branched structure in the molecular structure (B)
Aliphatic dicarboxylic acid compound or derivative thereof (C)
Trifunctional or higher functional polyol compound (D1)
Trifunctional or higher functional polycarboxylic acid compound or derivative thereof (D2) The polyester polyol resin according to claim 1, wherein the polyol compound (B) having a branched structure in the molecular structure is 2-methyl-1,3-propanediol. The polyester polyol resin according to claim 1, wherein the hydroxyl value is in the range of 2 to 100 mg KOH / g. A curable resin composition comprising a main agent containing the polyester polyol resin according to any one of claims 1 to 3 and a curing agent. A paint comprising the curable resin composition according to claim 4. A coated steel plate having a coating film comprising the paint according to claim 5.