JP2007039560A - Polyester resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester resin composition as a combination of a polyester resin of high glass transition temperature and an isocyanate curing agent, extremely quickly curable, and also giving coating film of excellent solvent resistance, stainproofness, processability and scratch resistance. <P>SOLUTION: The polyester resin composition comprises (A) a polyester resin meeting the requirements(1) to (5) described below, (B) a polyisocyanate resin and (C) a tin compound. The requirements are as follows: (1) provided that the amounts of the acid components total 100 mol%, the amount(s) of unsaturated bond-bearing dicarboxylic acid(s) stand at 0.5-50 mol%; (2) provided that the amounts of the acid components total 100 mol%, the amount(s) of aromatic carboxylic acid(s) stand at 50 mol% or greater; (3) a polymerization catalyst used is a titanium-based compound, the titanium atoms being contained at 10-200 ppm in the polyester resin; (4) the glass transition temperature is 10-100°C; and (5) the acid value is 2-150 equivalents/10<SP>6</SP>g. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polyester resin composition containing a high Tg polyester resin suitable for paints, coating agents and adhesives. More specifically, the present invention relates to a polyester resin composition suitable for various materials and having excellent curability, solvent resistance, stain resistance, workability, and scratch resistance.

  A combination of a polyester resin and an isocyanate compound has thermosetting properties and is used as various adhesives, paints, and coating agents. Isocyanate compounds are preferred because they can provide a sufficient crosslinking density with a small amount of use and can be cured at low temperatures compared to combinations of amino resins such as melamine resins, urea resins, and benzoguanamine resins used as curing agents and polyester resins. in use. Butylated melamine resins are generally used as curing agents in paints and coatings when they exhibit stain resistance, but melamine resins contain formaldehyde, which is a causative agent of sick house syndrome. There has been a demand for paints and coating agents that do not contain resin and have excellent stain resistance.

  The reaction between the polyester resin and the isocyanate compound often uses a hydroxyl group or carboxyl group at the molecular end or side chain of the polyester resin, or an amino group provided by modification or the like as a reaction site. However, the polyester resin and the polyisocyanate compound have a slow reaction rate and cannot obtain a sufficient crosslinking density. In particular, when the molecular weight of the polyester is increased, the reactivity is further reduced because the reactive sites are decreased. Accordingly, various approaches have been disclosed to remedy these drawbacks.

  In order to improve the reactivity, many hydroxyl groups and amino groups are often introduced into the polyester resin by modification or the like, and a combination of a trifunctional polyol and a polyisocyanate is disclosed (for example, see Patent Document 1). If the functional group increases, the production process may be gelled and the production process becomes complicated, and the distance between crosslinks of the cured product is shortened. For example, the polyester resin that has excellent processability loses its original physical properties, It may not be possible to obtain the performance.

  Moreover, although the method of introduce | transducing an epoxy into the isocyanate bridge | crosslinking of polyester (for example, refer patent document 2) or the adhesive agent (refer patent document 3) containing water as a main ingredient is disclosed, these are to raise the degree of hardening. Is effective, but the introduced epoxy or water may harden the adhesive layer and reduce the impact resistance.

  On the other hand, a technique for introducing a monomer having a double bond into a polyester resin having an extremely low glass transition temperature is disclosed for improving curability (see, for example, Patent Document 4), but a polyester having a relatively high glass transition temperature. In some cases, the resin may not allow a sufficient curing reaction to proceed.

JP-A-9-32239 (Claims) JP-A-8-199147 (Claims) JP-A-6-299135 (Claims) Japanese Unexamined Patent Publication No. 2004-2225013 (Claims)

  An object of the present invention is to enable extremely fast curing with a combination of a polyester resin having a high glass transition temperature and an isocyanate curing agent, which has not been obtained conventionally, and the coating film has excellent solvent resistance and contamination resistance. It is providing the industrially useful polyester resin composition by exhibiting property, workability, and scratch resistance.

  As a result of intensive investigation of the curing reaction between the polyester resin having a high glass transition temperature and the isocyanate curing agent, the present inventors have used a compound having a double bond, copolymerized the polyester resin using a titanium-based catalyst, By adding a specific amount of tin compound when blending paints, the reactivity with isocyanate compounds can be significantly improved despite the high glass transition temperature of the polyester resin, resulting in solvent resistance, stain resistance, workability, and scratch resistance. The present invention has been found. That is, this invention is the following polyester resin compositions.

A polyester resin composition comprising a polyester resin (A), a polyisocyanate resin (B) and a tin compound (C) that satisfy the following conditions (1) to (5).
(1) When the sum of the acid components is 100 mol%, 0.5 to 50 mol% of the acid components are dicarboxylic acids having an unsaturated bond.
(2) When the total of the acid components is 100 mol%, the aromatic dicarboxylic acid is 50 mol% or more.
(3) The polymerization catalyst is a titanium compound, and the titanium atom is contained in the polyester resin in an amount of 10 to 200 ppm.
(4) The glass transition temperature is 10 to 100 ° C.
(5) The acid value is 2 to 150 equivalents / 10 ⁶ g.

  The polyester resin composition of the present invention has conventionally obtained curing characteristics that could not be obtained with a combination of a polyester resin having a high glass transition temperature and an isocyanate curing agent, and has excellent solvent resistance, stain resistance, workability, and scratch resistance. It also has a tendency to attach. The composition of the present invention can be used as a paint for a precoat metal with a low environmental load and excellent stain resistance.

  As the constituent component of the polyester resin (A) used in the present invention, conventionally used dibasic acid component and glycol component can be used, and as the dibasic acid component, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, etc. Aromatic dibasic acid, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, dimer acid and other aliphatic dicarboxylic acids, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid And alicyclic dicarboxylic acids such as Of these, aromatic dicarboxylic acid is preferably copolymerized in an amount of 50 mol% or more from the viewpoint of improving solvent resistance, stain resistance, and scratch resistance. Among them, terephthalic acid and / or isophthalic acid is preferably 30 mol. % Or more copolymerized is preferable. Preferably it is 40 mol% or more, More preferably, it is 50 mol% or more.

  Examples of the glycol component include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3 -Methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, diethylene glycol, 1,4-cyclohexanedimethanol, Examples thereof include an ethylene oxide adduct of bisphenol A, a propylene oxide adduct of bisphenol A, or a polyether glycol such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol. Furthermore, lactones such as ε-caprolactone and δ-valerolactone, and oxycarboxylic acids such as p-hydroxyethoxybenzoic acid are also examples of raw materials for the polyester resin. Among these, it is preferable to make polyester resin (A) high specific gravity from a viewpoint of improving stain resistance, and it is preferable that the range is 1.21 or more and less than 1.36. Preferably it is 1.30 or more and less than 1.36. When the specific gravity exceeds 1.36, the stain resistance is improved, but the solvent solubility may be lowered. In order to obtain a polyester resin with a high specific gravity, a conventionally known method such as increasing the aromatic ring in the polyester resin or copolymerizing a glycol having a short chain length can be employed. A copolymer of ethylene glycol and ethyl ether glycol is preferred. When the ethylene glycol is 50 mol% or less, the Tg of the polyester resin is extremely low and the stain resistance is lowered. When the ethyl ether glycol is 10 mol% or less, the solvent solubility is lowered. 90 mol% and ethyl ether glycol are preferably copolymerized in an amount of 10 to 50 mol%. Examples of ethyl ether glycol include diethylene glycol, triethylene glycol, ethylene oxide adducts of bisphenol A, and the like. Of these, diethylene glycol is preferably copolymerized in order to increase Tg while satisfying solvent solubility.

  Trifunctional or higher functional components such as trimethylolpropane, pentaerythritol and trimellitic anhydride may be used in combination so as not to impair the physical properties of the polyester after the polyisocyanate crosslinking reaction.

  The polyester resin (A) used in the present invention is copolymerized with a dicarboxylic acid having an unsaturated bond in a part of the acid component. When the total amount of the acid components of the polyester resin is 100 mol%, the amount of copolymerization is It is preferable that it is 0.5-50 mol% of an acid component. More preferably, it is 2-30 mol%, More preferably, it is 5-20 mol%. The unsaturated bond is preferably a double bond. When the dicarboxylic acid containing an unsaturated bond is less than 0.5 mol%, the effect on the curability of the polyester resin (A) and the polyisocyanate compound (B) may be reduced, and when the dicarboxylic acid exceeds 50 mol%. The possibility of gelation due to the cleavage of unsaturated bonds increases, making it difficult to produce high molecular weight polyesters.

  Examples of the dicarboxylic acid containing an unsaturated double bond used in the polyester resin (A) used in the present invention include α, β-unsaturated dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, Examples of the alicyclic dicarboxylic acid containing an unsaturated double bond include 2,5-norbornane dicarboxylic acid anhydride and tetrahydrophthalic anhydride. Of these, fumaric acid, maleic acid and 2,5-norbornene dicarboxylic acid (endo-bicyclo- (2,2,1) -5-heptene-2,3- Dicarboxylic acid), and particularly preferred is fumaric acid.

  The amount of the titanium compound as a polymerization catalyst contained in the polyester resin (A) used in the present invention is 10 to 200 ppm, more preferably 15 to 100 ppm, still more preferably 20 to 80 ppm as a titanium atom in the polyester resin. If it is 10 ppm or less, the activity is extremely lowered when used as a catalyst, which is not preferable. If it is 200 ppm or more, the water resistance, heat resistance, and color tone of the coating film tend to decrease, such being undesirable.

  As a titanium compound used as a polymerization catalyst when polymerizing the polyester resin (A) used in the present invention, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetraisobutyl titanate, tetra-tert-tert- Examples thereof include butyl titanate, tetracyclohexyl titanate, tetraphenyl titanate, and tetrabenzyl titanate. Tetra-n-butyl titanate is particularly preferable.

  On the other hand, the polyester resin (A) used in the present invention is a polymerization catalyst such as an antimony compound, a germanium compound, a tin compound, and an aluminum compound, and the addition of these components is the water resistance and heat resistance of the coating film as described above. In the case of using them as a polymerization catalyst, it is effective to improve productivity by shortening the polymerization time, and it is preferable to use them together in a range of addition amounts that do not cause problems in color tone.

  The polyester resin (A) used in the present invention preferably contains a radical polymerization inhibitor. The amount is 10 to 800 ppm, more preferably 100 to 400 ppm as a radical polymerization inhibitor molecule in the polyester resin. If it is 10 ppm or less, there is a high possibility of gelation by double bond cleavage, and it may be difficult to produce a high molecular weight polyester. If it is 800 ppm or more, the polyester resin (A) may be colored, and the color tone of the coating film may be lowered and the appearance may be impaired.

  The radical polymerization inhibitor used in the present invention is mainly used to prevent gelation by double bond cleavage when polymerizing the polyester resin (A), and further to improve the curability of the paint. In order to increase the storage stability of the polymer, it may be added after polymerization. Examples of radical polymerization inhibitors include known antioxidants such as phenolic antioxidants, phosphorus antioxidants, amine antioxidants, sulfur antioxidants, and inorganic compound antioxidants.

  Examples of phenolic antioxidants include 2,5-di-t-butylhydroquinone, 4,4′-butyldenbis (3-methyl-6-t-butylphenol), 1,1,3-tris (2-methyl-4 -Hydroxy-5-tert-butylphenyl) butane, 1,3,5-tris-methyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3 , 5-di-t-butyl-4-hydroxyphenyl) isocyanurate, or a derivative thereof.

  Phosphorous antioxidants include tri (nonylphenyl) phosphite, triphenyl phosphite, diphenylisodecyl phosphite, trioctadecyl phosphite, tridecyl phosphite, diphenyldecyl phosphite, 4,4′-butylidene-bis (3-methyl-6-t-butylphenyl ditridecyl phosphite), distearyl-pentaerythritol diphosphite, trilauryl trithiophosphite, etc., or derivatives thereof.

  Amine antioxidants include phenyl-beta-naphthylamine, phenothiazine, N, N′-diphenyl-p-phenylenediamine, N, N′-di-betanaphthyl-p-phenylenediamine, and N-cyclohexyl-N′-. Examples include phenyl-p-phenylenediamine, aldol-alpha-naphthylamine, 2,2,4-trimethyl-1,2-dihydroquinoline polymer, and derivatives thereof.

  Examples of the sulfur-based antioxidant include thiobis (N-phenyl-beta-naphthylamine, 2-mercaptobenchazole, 2-mercaptobenzimidazole, tetramethylthiuram disulfide, nickel isopropyl xanthate, and derivatives thereof.

  Nitro compound antioxidants include 1,3,5-trinitrobenzene, p-nitrosodiphenylamine, p-nitrosodimethylaniline, 1-chloro-3-nitrobenzene, o-dinitrobenzene, m-dinitrobenzene, p-di Examples thereof include nitrobenzene, p-nitrobenzoic acid, nitrobenzene, 2-nitro-5-cyanothiophene, and derivatives thereof.

Examples of the inorganic compound antioxidant include FeCl ₃ , Fe (CN) ₃ , CuCl ₂ , CoCl ₃ , Co (ClO ₄ ) ₃ , Co (NO ₃ ) ₃ , and Co ₂ (SO ₄ ) ₃ .

  As the radical polymerization inhibitor used in the present invention, among the above-mentioned antioxidants, phenol-based antioxidants and amine-based antioxidants are preferable in terms of thermal stability, and the melting point is 120 ° C. or higher and the molecular weight is 200 or higher. More preferred are those having a melting point of 170 ° C. or higher. Specific examples include phenothiazine and 4,4'-butyldenbis (3-methyl-6-t-butylphenol).

  As for the glass transition temperature of the polyester resin (A) used for this invention, 10-100 degreeC is preferable, More preferably, it is 20-90 degreeC, More preferably, it is 30-80 degreeC. Below 10 ° C., the hardness of the coating film is low and the stain resistance and scratch resistance tend to decrease. If the temperature exceeds 100 ° C., the solution viscosity becomes high, and there may be a significant problem in operation.

The acid value of the polyester resin (A) used in the present invention is preferably 2 to 150 equivalents / 10 ⁶ g. If it exceeds 150 equivalents / 10 ⁶ g, carboxylic acid end groups that could not react with isocyanate during curing remain in the coating film, and the water resistance and heat resistance may decrease.

  The reduced viscosity of the polyester resin (A) used in the present invention is preferably 0.20 to 1.50 dl / g, more preferably 0.30 to 1.00 dl / g. If it is less than 0.20 dl / g, the toughness of the coating film may be inferior, and the workability tends to decrease. If it exceeds 1.50 dl / g, the solution viscosity becomes high, and there may be a significant problem in operation.

  As the polyisocyanate compound (B) of the present invention, conventionally used organic polyisocyanates such as aromatic, aliphatic and alicyclic can be used. Specific examples include naphthalene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, Examples thereof include organic polyisocyanates such as hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate, diphenylmethane diisocyanate, and tolylene diisocyanate, or modified polyvalent polyisocyanates or mixtures thereof. In particular, a polyisocyanate having a valence of 3 or more is preferable for curing the polyester resin.

  The polyisocyanate compound (B) can be blocked isocyanate by blocking the isocyanate group with a blocking agent. Examples of the blocking agent include alcohols, alkylphenols, phenols, active methylenes, mercaptans, acid amides, acid imides, imidazoles, ureas, oximes, amines, imides, pyrazoles, etc. There is.

Examples of more specific blocking agents are shown below.
(1) Alcohol type; methanol, ethanol, 2-propanol, n-butanol, sec-butanol, 2-ethyl-1-hexanol, 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, etc. (2) alkylphenol Mono- and dialkylphenols having an alkyl group having 4 or more carbon atoms as a substituent, for example, n-propylphenol, i-propylphenol, n-butylphenol, sec-butylphenol, t-butylphenol, n-hexyl Monoalkylphenols such as phenol, 2-ethylhexylphenol, n-octylphenol, n-nonylphenol, di-n-propylphenol, diisopropylphenol, isopropylcresol, di-n-butylphenol Dialkylphenols such as phenol, cresol, ethylphenol, di-tert-butylphenol, di-sec-butylphenol, di-n-octylphenol, di-2-ethylhexylphenol, di-n-nonylphenol (4) Active methylene series; dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, acetylacetone, etc. (5) mercaptan series; butyl mercaptan, dodecyl mercaptan, etc. (6) Acid amide type; acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam etc. (7) acid imide type; succinimide, maleic imide etc. (8) imidazole type; imidazole, 2-methyl (9) Urea type; urea, thiourea, ethylene urea, etc. (10) oxime type; formald oxime, acetald oxime, acetoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc. (11) amine type; diphenylamine, aniline, carbazole , N-propylamine, diisopropylamine, isopropylethylamine and the like (12) imine type; ethyleneimine, polyethyleneimine and the like (13) pyrazole type; pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like.

  The isocyanate group blocking agent is preferably at least one selected from alcohols, oximes, acid amides, active methylenes, and pyrazoles, and more preferably alcohols, oximes, active methylenes, and pyrazoles. Two or more blocking agents may be mixed.

As the tin compound (C) used in the present invention, conventionally used aromatic, aliphatic, alicyclic and other organic tins can be used. Specific examples include dibutyltin dilaurate, dioctyltin dilaurate, butyltin tri (2 -Organometallic compounds such as ethylhexanoate).
In addition, known urethanization catalysts such as organic amines such as triethylenediamine and triethylamine and their salts are allowed to coexist within a range of addition amounts that do not cause problems with solvent resistance, stain resistance, processability, and scratch resistance of the coating film. May be used.

  In this invention, you may use together thermosetting resins other than polyisocyanate compounds, such as a melamine resin, a urea resin, a benzoguanamine resin, and a phenol resin.

  The blend ratio of the polyester resin (A), polyisocyanate compound (B) and tin compound (C) used in the present invention is (A) / (B) / (C) = 100 / 0.5 to 30/0. 01 to 2.0 (parts by mass) is preferable, more preferably 100/1 to 25 / 0.05 to 1.0 (parts by mass), and most preferably 100/10 to 20 / 0.1 to 0. 5 (parts by mass).

  When the polyisocyanate compound (B) is less than 0.5 parts by mass with respect to 100 parts by mass of the polyester resin (A), the curability with the polyester resin is low, and the solvent resistance, stain resistance, workability, and scratch resistance of the coating film are low. When the amount exceeds 30 parts by mass, the isocyanate component becomes excessive and unreacted components remain in the cured coating film, which decreases the solvent resistance, stain resistance, workability, and scratch resistance of the coating film. Cause.

  If the tin compound (C) is less than 0.01 parts by mass relative to 100 parts by mass of the polyester resin (A), the curability with the polyester resin is low, and the solvent resistance, stain resistance, workability, and scratch resistance of the coating film are low. If the amount exceeds 2.0 parts by mass, the curing rate becomes too fast and the flowability is lowered, which may impair the appearance of the coating film after baking.

  In the entire composition in the present invention, the molar ratio of tin atoms to titanium atoms contained in the tin atom due to the tin compound (C) and the titanium atoms due to the polymerization catalyst of the polyester resin (A) is It is preferable that the number of moles / the number of moles of titanium is in the range of 0.1 to 10. More preferably, it exists in the range of 1-8.5, More preferably, it exists in the range of 4-6. If the number of moles of Sn / number of moles of Ti is less than 0.1, the curability with the polyester resin is low, and the solvent resistance, stain resistance, workability, and scratch resistance of the coating film tend to decrease. If it exceeds 1, the curing rate tends to decrease.

  The polyester resin composition of the present invention is effective for use in adhesives, coating agents, and coatings, and exhibits fast curing and low temperature curing effects, particularly when used as a precoat metal coating. Although the base material for apply | coating is not specifically limited, Plastic films, such as metals, such as iron, copper, and aluminum, polyethylene terephthalate, polyethylene, a polypropylene, are mentioned.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the term “parts” means parts by mass. Each item followed the following method.

1. Composition analysis ¹ H-NMR analysis was performed using a nuclear magnetic resonance analyzer (NMR) Gemini-200 manufactured by Varian in chloroform D solvent, and the integral ratio was determined.

2. Reduced viscosity 0.10 g of polyester resin was dissolved in 25 cc of a mixed solvent of phenol / tetrachloroethane (mass ratio 6/4) and measured at 30 ° C. The unit was expressed in dl / g.

3. Glass transition temperature It measured with the temperature increase rate of 20 degree-C / min using the differential scanning calorimeter (DSC). As a measurement sample, 5 mg of a sample was placed in an aluminum press-lid container and crimped.

4). Acid value 0.2 g of a sample was precisely weighed and dissolved in 20 ml of chloroform. Then, it was determined by titration with 0.01 N potassium hydroxide (ethanol solution), and the unit was expressed in equivalents / 10 ⁶ g. Phenolphthalein was used as an indicator.

5. Polyester resin, metal content in polyester resin composition (1) Titanium analysis 1 g of a sample was precisely weighed in a platinum crucible and carbonized and incinerated in an electric furnace. After the residue was melted with potassium hydrogen sulfate, the melt was dissolved with dilute hydrochloric acid, and the amount of titanium was determined using the diantipyrylmethane colorimetric method. The unit was expressed in ppm as a metal atom.
(2) Tin analysis 0.2 g of a sample was precisely weighed into a quartz Erlenmeyer flask and decomposed with sulfuric acid-hydrogen peroxide. The decomposition solution was transferred to a 20 ml volumetric flask using 10 ml of 6M hydrochloric acid and made up with purified water. Tin in the solution was determined using ICP emission spectrometry. The quantification was performed by a calibration curve method. The unit was expressed in ppm as a metal atom.

6). Solvent rub resistance The coated surface of the coated steel sheet was wiped 100 times while applying a load of 1 kg with felt containing xylene, and the coated surface was observed. The evaluation criteria are as follows.
A: Good with no change in the coating surface,
○: Slight scratches are observed on the coated surface and the curability is poor. Δ: Scratches are observed on the coated surface and the curability is poor.
X: The coating film surface is dissolved in xylene and the curability is extremely inferior.

7). Magic stain resistance Red magic ink was applied to the coated surface of the coated steel sheet and allowed to stand at room temperature for 48 hours, and then the traces of the magic ink applied with a soft cloth soaked in ethanol were visually observed.
◎: No trace of dirt is observed. ○: Slightly trace of dirt is observed. △: A trace of dirt remains. ×: A trace of dirt remains.

8). Workability The coated steel plate was bent 180 degrees, and cracks generated in the bent part were observed and judged with a 10-fold magnifier. 3T refers to the case where three sheets of the same thickness are sandwiched in the bent portion, and 0T refers to the case where the plate is folded 180 degrees without sandwiching the plate.

9. Pencil hardness The coated surface of the coated steel sheet was subjected to a pencil scratch test according to JIS-K-5400, and the hardness at which the scratch was not found was measured.

Polyester synthesis example (A)
In a reaction vessel equipped with a stirrer, a condenser, and a thermometer, terephthalic acid (hereinafter abbreviated as TPA) 259, isophthalic acid (hereinafter abbreviated as IPA) 227 parts, fumaric acid (hereinafter abbreviated as FA) 18 parts, trimellitic anhydride (hereinafter referred to as “after”) 6.10 parts of TMA), 326 parts of 2-methyl 1,3-propanediol (hereinafter abbreviated as 2MG), 158 parts of 1,4-cyclohexanedimethanol (hereinafter abbreviated as CHDM), tetrabutyl titanate 0 as a reaction catalyst .32 parts, 0.15 part of phenothiazine as a radical polymerization inhibitor was charged, and the esterification reaction was carried out from 160 ° C. to 240 ° C. over 4 hours. Next, the pressure in the system was gradually reduced, the pressure was reduced to 5 mmHg over 50 minutes, and a polycondensation reaction was performed at 250 ° C. for 30 minutes under a vacuum of 0.3 mmHg or less. Subsequently, it cooled to 220 degreeC under nitrogen stream, 6.10 parts of TMA was prepared, and it stirred for 30 minutes, and carboxyl modification of the terminal group was performed. In the compositional analysis, the acid component was TPA / IPA / FA / TMA / TMA (post-addition) = 49/44/5/1/1 in molar ratio and the glycol component was 2MG / CHDM = 71/29 in molar ratio. . The reduced viscosity was 0.55 dl / g, the glass transition temperature was 51 ° C., and the acid value was 85 equivalents / 10 ⁶ g. The results are shown in Table 1.

Polyester synthesis example (B)
In a reaction vessel similar to Synthesis Example (A), 547 parts of dimethyl terephthalate (hereinafter abbreviated as DMT), 73.1 parts of ethylene glycol (hereinafter abbreviated as EG), 359 parts of 1,2-propanediol (hereinafter abbreviated as PG) , Trimethylolpropane (hereinafter abbreviated as TMP), tetrabutyl titanate 0.31 part as a reaction catalyst, phenothiazine 0.12 part as a radical polymerization inhibitor, gradually heated to 220 ° C. over 4 hours, and distilled The transesterification reaction was performed while removing methanol to be removed from the system. Then, 17.4 parts of FA was charged and esterification was performed up to 230 ° C. over 90 minutes. Next, the pressure inside the system was gradually reduced, the pressure was reduced to 5 mmHg over 50 minutes, and a polycondensation reaction was performed at 250 ° C. for 50 minutes under a vacuum of 0.3 mmHg or less. In the compositional analysis, the acid component was TPA / FA = 95/5 in molar ratio, and the glycol component was EG / PG / TMP = 27 / 72.4 / 0.6 in molar ratio. The reduced viscosity was 0.53 dl / g, the glass transition temperature was 78 ° C., and the acid value was 19 equivalents / 10 ⁶ g. The results are shown in Table 1.

Polyester synthesis example (C)
In a reaction vessel similar to Synthesis Example (A), 282 parts of DMT, 282 parts of dimethyl isophthalate (hereinafter abbreviated as DMI), 322 parts of EG, 97.1 parts of diethylene glycol (hereinafter abbreviated as DEG), and 0.32 of tetrabutyl titanate as a reaction catalyst And 0.12 part of phenothiazine as a radical polymerization inhibitor were added, the temperature was gradually raised to 220 ° C. over 4 hours, and transesterification was performed while removing distilled methanol out of the system. Then, 17.7 parts of FA was charged and the esterification reaction was carried out up to 230 ° C. over 90 minutes. Next, the pressure in the system was gradually reduced, and the pressure was reduced to 5 mmHg over 50 minutes, and further a polycondensation reaction was performed at 250 ° C. for 60 minutes under a vacuum of 0.3 mmHg or less. In the compositional analysis, the acid component was TPA / IPA / FA = 48/47/5 in molar ratio, and the glycol component was EG / DEG = 77/23 in molar ratio. The reduced viscosity was 0.48 dl / g, the glass transition temperature was 49 ° C., and the acid value was 8 equivalents / 10 ⁶ g. The results are shown in Table 1.

Polyester synthesis example (D)
DMT246 part, DMI246 part, EG334 part, DEG101 part in reaction container similar to synthesis example (A), tetrabutyl titanate 0.33 part as a reaction catalyst, phenothiazine 0.24 part as a radical polymerization inhibitor are charged, and transesterification is carried out. The reaction was performed in the same manner as in Synthesis Example (C) except that 73.5 parts of FA was charged later. In the compositional analysis, the acid component was TPA / IPA / FA = 40/40/20 in molar ratio, and the glycol component was EG / DEG = 78/22 in molar ratio. The reduced viscosity was 0.53 dl / g, the glass transition temperature was 44 ° C., and the acid value was 6 equivalents / 10 ⁶ g. The results are shown in Table 1.

Polyester comparative synthesis example (E)
In the same reaction vessel as in Synthesis Example (A), 290 parts of IPA, 182 parts of SA, 35 parts of FA, 12 parts of TMA, 2 parts of MG271, 313 parts of neopentyl glycol (hereinafter abbreviated as NPG), 0.31 part of tetrabutyl titanate as a reaction catalyst, radical 0.14 part of phenothiazine was charged as a polymerization inhibitor, and an esterification reaction was performed from 160 ° C. to 240 ° C. over 4 hours. Next, the pressure in the system was gradually reduced, and the pressure was reduced to 5 mmHg over 50 minutes, and further a polycondensation reaction was performed at 250 ° C. for 60 minutes under a vacuum of 0.3 mmHg or less. In the composition analysis, the acid component was IPA / SA / FA / TMA = 58/30/10/2 in molar ratio, and the glycol component was 2MG / NPG = 55/45 in molar ratio. The reduced viscosity was 0.86 dl / g and the glass transition temperature was −6 ° C. The results are shown in Table 1.

Polyester comparative synthesis example (F)
The reaction was performed in the same manner as in Synthesis Example (A) except that 0.46 part of antimony trioxide was charged as a reaction catalyst. In the compositional analysis, the acid component was TPA / IPA / FA / TMA / TMA (post-addition) = 49/44/5/1/1 in molar ratio and the glycol component was 2MG / CHDM = 71/29 in molar ratio. . The reduced viscosity was 0.55 dl / g, the glass transition temperature was 51 ° C., and the acid value was 85 equivalents / 10 ⁶ g. The results are shown in Table 1.

Polyester synthesis example (G)
Charge DMT291, DMI291, EG316, DEG95.4, and tetrabutyltitanate 0.32 part as a reaction catalyst in the same reaction vessel as in Synthesis Example (A), and gradually raise the temperature to 220 ° C. over 4 hours. The transesterification was carried out while removing distilled methanol out of the system. Next, the pressure in the system was gradually reduced, and the pressure was reduced to 5 mmHg over 50 minutes, and further a polycondensation reaction was performed at 250 ° C. for 60 minutes under a vacuum of 0.3 mmHg or less. In the compositional analysis, the acid component was TPA / IPA = 50/50 in molar ratio, and the glycol component was EG / DEG = 78/22 in molar ratio. The reduced viscosity was 0.49 dl / g, the glass transition temperature was 50 ° C., and the acid value was 7 equivalents / 10 ⁶ g. The results are shown in Table 1.

Preparation of Polyester Resin Composition (a) 100 parts of the polyester resin of Synthesis Example (A) is dissolved in 233 parts of cyclohexanone, and a trimer of 3,5-dimethylpyrazole block type hexamethylene diisocyanate as a polyisocyanate compound (solid content) 20 parts by weight (concentration 75% by mass), 120 parts by weight of titanium oxide (CR-93 manufactured by Ishihara Sangyo Co., Ltd.) as a white pigment, 0.5 parts by weight of butyltin tri (2-ethylhexanoate) as a curing catalyst, As a leveling agent, 0.5 part by weight of Polyflow S (manufactured by Kyoeisha Chemical Co., Ltd.) was added and dispersed for 5 hours with a glass bead type high speed shaker to obtain a polyester resin composition (a). Table 2 shows the compounding ratio and the molar ratio of tin atoms and titanium atoms contained in the polyester resin composition.

Preparation of polyester resin compositions (b) to (f) Polyester resin compositions (b) to (f) were prepared in the same manner as polyester resin compositions (a) using the polyester resins of Synthesis Examples (B) to (F). ) Table 2 shows the compounding ratio and the molar ratio of tin atoms and titanium atoms contained in the polyester resin composition.

Preparation of primer coating (g) Commercially dissolved high molecular weight polyester (Byron 296 manufactured by Toyobo Co., Ltd., solid content concentration 40% by mass) 100 solid parts 50 parts titanium oxide, hexamethoxylated melamine as a curing agent (Mitsui Cytex Co., Ltd., Cymel 303, solid content concentration: 60% by mass) 20 solid parts, 2.5 parts of a 10% benzyl alcohol solution of p-toluenesulfonic acid as a curing catalyst were added, and a glass bead type shaker was used. A primer paint was prepared by dispersing for 5 hours. As the solvent, an appropriate amount of a cyclohexanone / solvesso (manufactured by Exxon Chemical) 150 = 50/50 (mass ratio) mixture was used.

Preparation of primer-coated steel sheet A 0.5 mm thick galvanized steel sheet treated with chromate was used as a base material. Primer paint (g) was applied to this substrate so that the dry film pressure was 5 μm, and baked at 210 ° C. for 50 seconds.

Example 1
The polyester resin composition (a) was applied onto a primer-coated steel plate using a bar coater so as to have a thickness of 18 μm after being baked, and dried with a hot air dryer at 235 ° C. for 50 seconds. Immediately after drying, the coated steel sheet was immersed in cold water, cooled to below room temperature, and after removing moisture, a predetermined test was performed. The results are shown in Table 3.

Examples 2-4
The polyester resin compositions (b) to (d) were evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Examples 1-3
Comparative polyester resin compositions (e) to (g) were evaluated in the same manner as in Example 1. The results are shown in Table 3.

  As is clear from Table 3, Examples 1 to 4 using a polyester resin obtained by copolymerizing a monomer having a double bond using a titanium compound as a polyester polymerization catalyst were more resistant to solvents (cured). It can be seen that the processability is excellent. In particular, Examples 3 and 4 using a polyester resin having a specific gravity of 1.3 or more are found to be excellent in stain resistance. Further, Comparative Example 2 using a polyester polymerization catalyst other than a titanium-based compound does not show the effect of improving the solvent resistance and workability despite the polyester resin copolymerized with a monomer having a double bond. From this, it is effective to increase the effect of copolymerizing a compound having a double bond in the polyester resin by using a titanium compound as a polyester polymerization catalyst and adding a specific amount of tin compound at the time of coating. I understand that.

  The polyester resin composition of the present invention has conventionally obtained curing characteristics that could not be obtained with a combination of a polyester resin having a high glass transition temperature and an isocyanate curing agent, and has excellent solvent resistance, stain resistance, workability, and scratch resistance. It also has a tendency to attach. The composition of the present invention can be used as a paint for a precoat metal with a low environmental load and excellent stain resistance.

Claims (5)

A polyester resin composition comprising a polyester resin (A), a polyisocyanate resin (B) and a tin compound (C) that satisfy the following conditions (1) to (5).
(1) When the sum of the acid components is 100 mol%, 0.5 to 50 mol% of the acid components are dicarboxylic acids having an unsaturated bond.
(2) When the total of the acid components is 100 mol%, the aromatic dicarboxylic acid is 50 mol% or more.
(3) The polymerization catalyst is a titanium compound, and the titanium atom is contained in the polyester resin in an amount of 10 to 200 ppm.
(4) The glass transition temperature is 10 to 100 ° C.
(5) The acid value is 2 to 150 equivalents / 10 ⁶ g.   The compounding ratio of the polyester resin (A), the polyisocyanate resin (B), and the tin compound (C) is (A) / (B) / (C) = 100 / 0.5 to 30 / 0.01 to 2.0. It is (mass ratio), The polyester resin composition of Claim 1 characterized by the above-mentioned.   In the molar ratio of the tin atom resulting from the tin compound (C) and the titanium atom resulting from the polymerization catalyst of the polyester resin (A), the value of (number of moles of tin ÷ number of moles of titanium) is in the range of 0.1 to 10. The polyester resin composition according to claim 1 or 2, wherein   The polyester resin composition according to any one of claims 1 to 3, wherein the specific gravity of the polyester resin (A) is 1.21 or more and less than 1.36.   The polyester resin composition according to claim 1, wherein the polyester resin composition is used for a precoat metal coating.