DE112017008223T5 - (Meth) acrylic modified polyester resin, curable resin composition, paint and painted steel sheet - Google Patents

Abstract

The present invention provides a (meth) acrylic-modified polyester resin in which a saturated polyester resin (A) and a (meth) acrylic monomer mixture (B) comprising a hydroxyl group-containing (meth) acrylic monomer are used as required reaction raw materials, and the (meth) acrylic-modified one Polyester resin is characterized in that the saturated polyester resin (A) is a polycondensate of an aliphatic diol (a1) and a dicarboxylic acid (a2) comprising an aliphatic dicarboxylic acid, the content of the aliphatic dicarboxylic acid being 5% by weight or more in the dicarboxylic acid (a2) is. The (meth) acrylic-modified polyester resin enables high strengthening of paints and can form a paint film with excellent workability and weather resistance.

Description

Technical field

The present invention relates to a (meth) acrylic-modified polyester resin, a curable resin composition comprising the same, a paint consisting of the curable resin composition and a painted steel sheet with a paint film of the paint.

background

As a painting process of various metal parts or metal molded products for electrical household appliances, automotive parts, building materials, can manufacturing applications, etc., a pre-painting process (pre-coat method), in which a steel sheet is previously coated, and a re-painting process (post-coat method), in which a Painting is done after forming a steel sheet. A steel sheet that is used in pre-painting processes is generally referred to as pre-painted metal (hereinafter abbreviated as “PCM”). The previously painted steel sheet is used in various forms after cutting, depending on the intended use and the shape, so that PCM paints require very high workability and weather resistance in addition to the hardness or gloss of the paint film surface.

In recent years, taking into account the environmental impact, a high-strength PCM varnish has also been investigated, which has a low solvent content with a reduced amount of a volatile organic compound (FOV). A high solidification of paints is therefore necessary.

As conventional PCM paints, varnishes of various shapes are used, such as. B. Two-component curing type, ultraviolet curing type and volatilizing drying type. There are also a variety of resin systems, such as B. polyester resin, fluororesin and acrylic resin. Of these, because of excellent workability, a two-component curing type paint is widely used, which contains a polyester resin as the main substance.

As a varnish of the two-component curing type, which contains a polyester resin as the main substance, one is generally known which contains a polyester resin with a number average molecular weight (Mn) of 11,000 as the main substance and in which, as the reaction raw materials, e.g. B. terephthalic acid, isophthalic acid, 2-methyl-1,3-propanediol and 1,6-hexanediol can be used (see, for example, Patent Document 1). The varnish is characterized by workability, but it does not meet the criteria for high strengthening of varnishes that have been demanded in recent years.

For this reason, a material was required which was able to solidify paints to a high degree and form a paint film with excellent workability and weather resistance.

State of the art

[Patent document]

Patent Document 1: JP Patent Laid-Open No. H09-12969

Overview of the invention

Object of the invention to be solved

The object of the present invention is now to provide a (meth) acrylic-modified polyester resin which enables high strengthening of paints and can form a paint film with excellent workability and weather resistance, a curable resin composition comprising the (meth) acrylic-modified polyester resin, a paint and a to provide painted sheet steel.

Means to solve the task

As a result of intensive studies to achieve the above object, the inventors of the present invention found that by using a (meth) acrylic-modified polyester resin in which a saturated polyester resin and a (meth) Acrylic monomer mixture can be used, the above object can be achieved, whereby the present invention has been completed.

The present invention relates to a (meth) acrylic-modified polyester resin in which a saturated polyester resin (A) and a (meth) acrylic monomer mixture (B) comprising a hydroxyl group-containing (meth) acrylic monomer are used as required reaction raw materials, and which is characterized in that saturated polyester resin (A) is a polycondensate of an aliphatic diol (a1) and a dicarboxylic acid (a2) comprising an aliphatic dicarboxylic acid, the content of the aliphatic dicarboxylic acid being 5% by weight or more in the dicarboxylic acid (a2) and one the curable resin composition comprising (meth) acrylic modified polyester resin, a varnish and a painted steel sheet.

Effect of the invention

The (meth) acrylic modified polyester resin of the present invention enables high strengthening of paints, i.e. H. Bring to a high non-volatile content, and formation of a paint film with excellent workability and weather resistance, so that it for PCM paints or paints for automobiles such. B. automotive top coats and automotive refinishes, can be used sensibly. “High solidification” in the present invention means that the non-volatile content of paints is 65% by weight or more.

Embodiment of the invention

The (meth) acrylic modified polyester resin of the present invention is characterized in that a saturated polyester resin (A) and a (meth) acrylic monomer mixture (B) are used as the required reaction raw materials.

The saturated polyester resin (A) stands for a polyester resin which has essentially no aliphatic carbon-carbon double bond.

As the saturated polyester resin (A), there is used one obtained by a polycondensation reaction of an aliphatic diol (a1) with a dicarboxylic acid (a2).

In the case of the aliphatic diol (a1), it is preferred that it contains an asymmetric diol with at least one side chain and / or a linear diol without side chains, since a (meth) acrylic-modified polyester resin is obtained which enables high strengthening of paints and a paint film with excellent machinability and weather resistance. The “asymmetric diol” in the present invention stands for diols with an asymmetrical structure.

As an asymmetric diol with at least one side chain z. B. 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,4-butanediol, 2-ethyl-1,4-butanediol, 2-methyl-1,3-propanediol, 3-methyl- 1,5-pentanediol and 3-methyl-1,5-heptanediol. These asymmetric diols with at least one side chain can be used both alone and in combination of two or more. Of these, 2-methyl-1,3-propanediol is also preferred.

As a linear diol without side chains z. B. ethylene glycol, diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nanodiol, 1, 10-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,15-pentadecanediol, 1,16-hexadecanediol, 1,17-heptadecanediol, 1,18- Octadecanediol, 1,19-nonadecanediol and 1,20-eicosanediol. These linear diols without side chains can be used alone or in combination of two or more. Of these, 1,6-hexanediol is also preferred because a (meth) acrylic-modified polyester resin is obtained, which enables high strengthening of paints and can form a paint film with excellent workability and weather resistance.

As the aliphatic diol (a1), other diols can be used in addition to the asymmetric diols with at least one side chain and the linear diols without side chains as required.

Examples of aliphatic diols other than those mentioned are e.g. B. neopentyl glycol, hydrogenated bisphenol A, hydrogenated bisphenol F, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,2- Hexanediol, 1,4-hexanediol, 2,3-hexanediol, 2,2-diethyl-1,3-propanediol, 1, 4-cyclohexanedimethanol and 1,4-cyclohexanediol. These other aliphatic diols can be used alone or in combination of two or more.

The essential component of the dicarboxylic acid (a2) is an aliphatic dicarboxylic acid, since a (meth) acrylic-modified polyester resin is obtained which can form a lacquer film with excellent workability and weather resistance.

As aliphatic dicarboxylic acid z. B. succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, cyclohexanedicarboxylic acid, dimer acid and fumaric acid, or methyl esters or acid chlorides of these aliphatic dicarboxylic acids. These aliphatic dicarboxylic acids can be used alone or in combination of two or more. Of these, adipic acid is preferred.

The content of aliphatic dicarboxylic acid in the dicarboxylic acid (a2) is 5% by weight or more due to the excellent compatibility with the (meth) acrylic monomer mixture (B). The range of 10 to 20% by weight is particularly preferred.

As the dicarboxylic acid (a2), an alicyclic or aromatic dicarboxylic acid or an acid anhydride of one of the two can also be contained, as required. As alicyclic dicarboxylic acid z. B. 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. As an aromatic dicarboxylic acid such. B. terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-p, p'-dicarboxylic acid, p-hydroxybenzoic acid, p- (2-hydroxyethoxy) benzoic acid, trimellitic acid, pyromellitic acid and phthalic anhydride.

In the case of a polycondensation reaction of the aliphatic diol (a1) with the dicarboxylic acid (a2), an esterification catalyst can be used as required.

As an esterification catalyst, for. B. metal salts such as titanium, tin, zinc, aluminum, zirconium, magnesium, hafnium and germanium; Metal compounds such as titanium tetraisopropoxide, titanium tetrabutoxide, titanium oxyacetylacetonate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, tin octoate, 2-ethylhexanoate tin, zinc acetylacetonate, zirconium tetrachloride, a zirconium tetrachloride tetrachloro tetrachloride, hafetachidium tetrachloride, hafetachidium tetrachloride, hafl tetrachloride, hafl tetrachloride, hafl tetrachloride, hafl tetrachloride, hafl tetrachloride, hafl tetrachloride, complex tetrachloride tetrachloride,

Furthermore, a reaction of the aliphatic diol (a1) with the dicarboxylic acid (a2) z. B. without solvent or in the presence of an organic solvent.

Even if a reaction of the aliphatic diol (a1) with the dicarboxylic acid (a2) is carried out without a solvent, a reactant by dissolving in an organic solvent can be used after the reaction.

As an organic solvent such. B. ketone solvents such as methyl ethyl ketone, acetone and isobutyl ketone; cyclic ether solvents such as tetrahydrofuran and dioxolane; Ester solvents such as methyl acetate, ethyl acetate and butyl acetate; aromatic solvents such as toluene, xylene and solvent naphtha; alicyclic solvents such as cyclohexane and methylcyclohexane; alcoholic solvents such as carbitol, cellosolve, methanol, isopropanol, butanol and propylene glycol monomethyl ether; Glycol ether solvents such as alkylene glycol monoalkyl ether, dialkylene glycol monoalkyl ether and dialkylene glycol monoalkyl ether acetate are listed. These organic solvents can be used alone or in combination of two or more.

It is preferred that the weight average molecular weight of the saturated polyester resin (A) is in the range from 1,000 to 5,000 and particularly preferably in the range from 2,000 to 3,000, since a (meth) acrylic-modified polyester resin is obtained which enables high strengthening of paints and one Paint film with excellent workability and weather resistance can form.

The weight average molecular weight of the saturated polyester resin (A) shows a value measured by a gel permeation chromatography (GPC) method.

The (meth) acrylic monomer mixture (B) comprises a hydroxyl-containing (meth) acrylic monomer as an essential component.

As a hydroxyl group-containing (meth) acrylic monomer, a (meth) acrylic monomer is mentioned which has a hydroxyl group in the molecule of e.g. B. 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and mono (meth) acrylate ester of glycerol. These hydroxyl group-containing (meth) acrylic monomers can be used both alone and in combination of two or more.

It is further preferred that the content of the hydroxyl group-containing (meth) acrylic monomer is 10% by weight or more in the (meth) acrylic monomer mixture. Especially when the (meth) acrylic modified polyester resin of the present invention is used for industrial paints, etc. such as. B. automobiles and heavy machinery, it is particularly preferred that the content is in the range of 20 to 40 wt .-%, and when it is used for PCM varnishes, etc., it is particularly preferred that the content in Range is 10 to 25 wt .-%.

In addition to the (meth) acrylic monomer containing hydroxyl groups, the (meth) acrylic monomer mixture can also contain other (meth) acrylic monomers.

As other (meth) acrylic monomers such. B. alkyl ester (meth) acrylate such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexel (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, Phenyl (meth) acrylate, and benzyl (meth) acrylate; a carboxyl group-containing (meth) acrylic monomer such as (meth) aclylate, β-carboxyethyl (meth) acrylate, 2- (meth) acryloylpropionic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, itaconic acid semi-ester, maleic acid half-ester, maleic anhydride, itaconic acid and methoxy succinate methacrylate, β- β- (meth) hydroxyethyl hydrogen phthalate and salts thereof; an amido group-containing (meth) acrylic monomer such as aminoethyl (meth) acrylate, N-monoalkylaminoalkyl (meth) acrylate, N, N-dialkylaminoalkyl (meth) acrylate, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propylacrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide and N, N- Diethyl (meth) acrylamide; Vinyl ester compounds such as acrolein, vinyl acetate, vinyl propionate and vinyl versatate; Vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, amyl vinyl ether and hexyl vinyl ether; Vinyl nitrile compounds such as (meth) acrylonitrile; an aromatic ring vinyl monomer such as styrene, α-methylstyrene, vinyltoluene, vinylanisole, α-halostyrene and vinylnaphthalene; a vinyl monomer without a functional group such as isoprene, butadiene and ethylene; a heterocyclic vinyl monomer such as N-vinyl pyrrolidone; and a phosphoric acid group-containing (meth) acrylic monomer such as (meth) acryloyloxyethyl phosphate, di (meth) acryloyloxyethyl phosphate, tri (meth) acryloyloxyethyl phosphate and caprolactone modified (meth) acryloyloxyethyl phosphate. These other (meth) acrylic monomers can be used alone or in combination of two or more.

The weight ratio [(A) / (B)] of the saturated polyester resin (A) to the (meth) acrylic monomer mixture (B) is preferably in the range from 15/85 to 50/50 and particularly preferably in the range from 25/75 to 35/65 , since a (meth) acrylic-modified polyester resin is obtained which enables high strengthening of paints and can form a paint film with excellent workability and weather resistance.

The (meth) acrylic modified polyester resin of the present invention can e.g. B. by dropping the (meth) acrylic monomer mixture (B) and a polymerization initiator into an organic solvent solution of the saturated polyester resin (A) and by reacting them.

As a polymerization initiator, for. B. Azo compounds such as 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-methylbutyronitrile) and azobiscyanovaleric acid; organic peroxides such as tert-butyl peroxypivalate, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, di-tert-butyl peroxide, cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide and tert-butyl peroxy-2-ethylhexyl monocarbonate; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate. These polymerization initiators can be used alone or in combination of two or more.

The weight average molecular weight of the (meth) acrylic-modified polyester resin of the present invention is preferably in the range from 5,000 to 20,000 and particularly preferably in the range from 7,500 to 12,500, since a (meth) acrylic-modified polyester resin is obtained which enables high strengthening of paints and a paint film with excellent machinability and weather resistance.

The hydroxyl number of the (meth) acrylic acid polyester resin of the present invention is preferably in the range from 60 to 150, since a (meth) acrylic-modified polyester resin is obtained which enables high strengthening of paints and a paint film with excellent workability and Weather resistance can form. Especially when the (meth) acrylic modified polyester resin of the present invention is used for industrial paints, etc. such as. B. automobiles and heavy machinery, it is particularly preferred that the hydroxyl number is in the range of 100 to 150, and when used for PCM varnishes, etc., it is particularly preferred that the hydroxyl number is in the range of 60 to 100 lies.

The curable resin composition of the present invention comprises the (meth) acrylic modified polyester resin and a curing agent as essential components.

The curing agent may comprise components as far as a curing reaction can be caused with the (meth) acrylic modified polyester resin of the present invention. As such components such. B. an amino resin, a polyisocyanate resin, a resol resin and an epoxy resin. These can be used alone or in combination of two or more. However, the components of the curing agent are selected depending on the use or environment of the curable resin composition or the physical properties of the desired cured product, etc., according to the circumstances. No matter which curing agent is used, the effect achieved by the present invention, i. H. excellent balance between workability and weather resistance in the hardened paint film, sufficiently demonstrated if the (meth) acrylic modified polyester resin of the present invention is used as the main substance.

As amino resin z. B. a methylolated amino resin obtained by synthesizing at least one component selected from the group consisting of melamine, urea and benzoguanamine with formaldehyde; and a resin is given which is obtained by alkyl esterification of part or all of the methylol groups of the methylolated amino resin with a lower monohydric alcohol such as methanol, ethanol, propanol, isopropanol, butanol and isobutanol.

As market products with amino resin z. B. "Cymel 303" (methylated melamine resin) and "Cymel 350" (methylated melamine resin) manufactured by Allnex and "U-Van 520" (n-butylated modified melamine resin), "U-Van 20-SE-60" (n- butylated modified melamine resin), "U-Van 2021" (n-butylated modified melamine resin), "U-Van 220" (n-butylated modified melamine resin), "U-Van 22R" (n-butylated modified melamine resin), "U- Van 2028 ”(n-butylated modified melamine resin),“ U-Van 165 ”(isobutylated modified melamine resin),“ U-Van 114 ”(isobutylated modified melamine resin),“ U-Van 62 ”(isobutylated modified melamine resin) and“ U- Van 60R ”(isobutylated modified melamine resin) manufactured by Mitsui Chemicals, Inc. When using these amino resins, an acid compound such as. B. a phosphoric acid ester can be added as a curing accelerator.

As polyisocyanate resin, for. B. aliphatic diisocyanate compounds such as butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate; alicyclic diisocyanate compounds such as norbornane diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate and hydrogenated diphenylmethane diisocyanate; aromatic diisocyanate compounds such as tolylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, diphenylmethane diisocyanate and 1,5-naphthalene diisocyanate; Polymethylene polyphenyl polyisocyanate having a repeating structure represented by the structural formula (1) below; one of an isocyanurate-modified, biuret-modified or allophanate-modified product and a blocked polyisocyanate resin.

worin R¹ unabhängig voneinander eines von einem Wasserstoffatom oder einer Kohlenwasserstoffgruppe mit 1 bis 6 Kohlenstoffatomen ist; R² unabhängig voneinander eines von einer Alkylgruppe mit 1 bis 4 Kohlenstoffatomen oder einem Bindungspunkt ist, der über eine mit * gekennzeichnete Methylengruppe mit der durch die Strukturformel (1) dargestellten Strukturstelle verbunden ist; m 0 oder eine ganze Zahl von 1 bis 3 und I eine ganze Zahl gleich oder größer 1 ist.

wherein R ^{1 is} independently one of a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms; R ^{2 is} independently one of an alkyl group having 1 to 4 carbon atoms or a bond point which is connected via a methylene group marked with * to the structural site represented by structural formula (1); m is 0 or an integer from 1 to 3 and I is an integer equal to or greater than 1.

As epoxy resin z. B. a polyglycidyl ether of a polyol compound, a polyglycidyl ester of a polycarboxylic acid compound, an epoxy resin of the bisphenol type and an epoxy resin of the novolak type.

The curable resin composition of the present invention may contain, as needed, a curing catalyst, a curing accelerator, a pigment, a pigment dispersant, a matting agent, a leveling agent, a drying inhibitor, a UV absorber, an anti-foaming agent, a thickening agent, an anti-settling agent, an organic solvent, etc. be added. The mixing ratio of each of these components and the type of formulation are adjusted according to the circumstances depending on the purpose or the desired performance of the curable resin composition. Furthermore, the curable resin composition of the present invention may contain both one component and two components. When the curable resin composition of the present invention contains two components, the various additives may be added to one or both of the main substance and the curing agent.

Although the use of the curable resin composition of the present invention is not particularly limited, it can be used for varnish or adhesive applications because of the ability to form a cured paint film with excellent workability and weather resistance. In particular, it can be used for PCM paints or paints for automobiles such. B. automotive top coats and automotive refinish paints can be used as a paint for painted steel sheets.

The painted steel sheet of the present invention means one that has a hardened paint film of a paint consisting of the hardened resin composition on the surface thereof. As steel sheet z. B. a galvanized steel sheet, a plated steel sheet such as a steel sheet made of aluminum-zinc alloy and a zinc-aluminum-magnesium alloy, an aluminum sheet, an aluminum alloy sheet, an electromagnetic steel sheet, a copper sheet and a stainless steel sheet.

Embodiments

The present invention is explained in detail below on the basis of exemplary embodiments and comparative examples.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the saturated polyester resin used in the present invention, and the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the (meth) acrylic-modified polyester resin of the present invention are the values by measurement under the following conditions by a gel permeation chromatography (GPC) method.

$$„\text{TSKgel G4000}”\left(\mathrm{7,8}\text{mm Innendurchmesser}\times \text{30cm}\right)\times 1$$

$$„\text{TSKgel G3000}”\left(\mathrm{7,8}\text{mm Innendurchmesser}\times \text{30cm}\right)\times 1$$

$$„\text{TSKgel G2000}”\left(\mathrm{7,8}\text{mm Innendurchmesser}\times \text{30cm}\right)\times 1$$

Detektor: RI (Differentialrefraktometer)
Säulentemperatur: 40 °C
Eluent: Tetrahydrofuran (THF)
Strömungsgeschwindigkeit: 1,0 ml / min.
Injektionsvolumen: 100 µl (Tetrahydrofuranlösung mit einer Probenkonzentration von 0,4 Gew.-%)
Standardprobe: unter Verwendung der nachstehenden Standardpolystyrole wurden Kalibrierungskurven erstellt.Measuring device: high-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation),
Column: The following columns manufactured by Tosoh Corporation were connected in series and used. $$"\text{TSKgel G5000}”\left(7.8\text{mm inside diameter}\times \text{30 cm}\right)\times 1$$

$$"\text{TSKgel G4000}”\left(7.8\text{mm inside diameter}\times \text{30 cm}\right)\times 1$$

$$"\text{TSKgel G3000}”\left(7.8\text{mm inside diameter}\times \text{30 cm}\right)\times 1$$

$$"\text{TSKgel G2000}”\left(7.8\text{mm inside diameter}\times \text{30 cm}\right)\times 1$$

Detector: RI (differential refractometer)
Column temperature: 40 ° C
Eluent: tetrahydrofuran (THF)
Flow rate: 1.0 ml / min.
Injection volume: 100 µl (tetrahydrofuran solution with a sample concentration of 0.4% by weight)
Standard Sample: Calibration curves were created using the standard polystyrenes below.

(Standard polystyrene)

"TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

(Production example 1: Preparation of a solution of a saturated polyester resin (1)) 5 parts by weight of 2-methyl-1,3-propanediol, 8.95 parts by weight of 1,6-hexanediol, 4 were placed in a reaction vessel with a stirrer, a condenser and a thermometer Parts by weight of trimethylolpropane, 28.29 parts by weight of neopentyl glycol, 44.76 parts by weight of isophthalic acid, 9 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate. An esterification reaction was carried out at 200 to 250 ° C for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (1) was obtained. The saturated polyester resin (1) had a number average molecular weight (Mn) of 1,094, a weight average molecular weight (Mw) of 2,114, an acid value of 2.8 mg KOH / g and a hydroxyl number of 137 mg KOH / g.

The obtained saturated polyester resin (1) was dissolved in butyl acetate to obtain a solution of the saturated polyester resin (1) having a non-volatile content of 81.4% by weight. The Gardner viscosity of the solution of the saturated polyester resin (1) was Z4 - Z5.

(Production example 2: Preparation of a solution of a saturated polyester resin (2)) In a reaction container with a stirrer, a condenser and a thermometer were placed 15.59 parts by weight of 2-methyl-1,3-propanediol and 10.25 parts by weight of 1,6-hexanediol , 1.97 parts by weight of trimethylolpropane, 17.64 parts by weight of neopentyl glycol, 44.3 parts by weight of isophthalic acid, 10.25 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate. An esterification reaction was carried out at 200 to 250 ° C for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (2) was obtained. The saturated polyester resin (2) had a number average molecular weight (Mn) of 988, a weight average molecular weight (Mw) of 2,026, an acid value of 2.1 mg KOH / g and a hydroxyl number of 141.3 mg KOH / g.

The obtained saturated polyester resin (2) was dissolved in butyl acetate to obtain a solution of the saturated polyester resin (2) having a non-volatile content of 83.1% by weight. The Gardner viscosity of the solution of the saturated polyester resin (2) was Z3-Z4.

(Production example 3: Preparation of a solution of a saturated polyester resin (3)) 30 parts by weight of 2-methyl-1,3-propanediol, 10 parts by weight of 1,6-hexanediol and 1 part by weight of trimethylolpropane were placed in a reaction container with a stirrer, a condenser and a thermometer , 4 parts by weight of neopentyl glycol, 35 parts by weight of isophthalic acid, 20 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate. An esterification reaction was carried out at 200 to 250 ° C. for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (3) was obtained. The saturated polyester resin (3) had a number average molecular weight (Mn) of 667, a weight average molecular weight (Mw) of 1,441, an acid value of 7.2 mg KOH / g and a hydroxyl number of 169.2 mg KOH / g.

The obtained saturated polyester resin (3) was dissolved in butyl acetate to obtain a solution of the saturated polyester resin (3) having a non-volatile content of 87% by weight. The Gardner viscosity of the solution of the saturated polyester resin (3) was Z2-Z3.

(Production example 4: Preparation of a solution of a saturated polyester resin (4)) In a reaction container with a stirrer, a condenser and a thermometer were placed 23.32 parts by weight of 2-methyl-1,3-propanediol and 3.89 parts by weight of 1,6-hexanediol , 1.94 parts by weight of trimethylolpropane, 12.05 Parts by weight of neopentyl glycol, 45.19 parts by weight of isophthalic acid, 13.61 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate are used. An esterification reaction was carried out at 200 to 250 ° C. for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (4) was obtained. The saturated polyester resin (4) had a number average molecular weight (Mn) of 2,149, a weight average molecular weight (Mw) of 4,968, an acid value of 4.7 mg KOH / g and a hydroxyl number of 78.6 mg KOH / g.

The obtained saturated polyester resin (4) was dissolved in a mixed solvent of 800 parts by weight of an aromatic based solvent ("Solvesso 100" made by ExxonMobil YK) and 200 parts by weight of propylene glycol monomethyl ether acetate to give a solution of the saturated polyester resin (4) having a nonvolatile content of 78 To get 3% by weight. The Gardner viscosity of the solution of the saturated polyester resin (4) was Z-Z1.

(Production Example 5: Preparation of a Solution of a Saturated Polyester Resin (5)) 30.81 parts by weight of 2-methyl-1,3-propanediol and 6.85 parts by weight of 1,6-hexanediol were placed in a reaction container with a stirrer, a condenser and a thermometer , 1.17 parts by weight of trimethylolpropane, 4.25 parts by weight of neopentyl glycol, 38.44 parts by weight of isophthalic acid, 18.49 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate. An esterification reaction was carried out at 200 to 250 ° C for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (5) was obtained. The saturated polyester resin (5) had a number average molecular weight (Mn) of 1,234, a weight average molecular weight (Mw) of 2,998, an acid value of 6 mg KOH / g and a hydroxyl number of 113.5 mg KOH / g.

The obtained saturated polyester resin (5) was dissolved in butyl acetate to obtain a solution of the saturated polyester resin (5) having a non-volatile content of 82.2% by weight. The Gardner viscosity of the saturated polyester resin solution (5) was X-Y.

(Production example 6: Preparation of a solution of a saturated polyester resin (6)) In a reaction container with a stirrer, a condenser and a thermometer were placed 25.76 parts by weight of 2-methyl-1,3-propanediol, 2.02 parts by weight of trimethylolpropane, 12.63 Parts by weight of neopentyl glycol, 40.4 parts by weight of isophthalic acid, 16.67 parts by weight of terephthalic acid, 2.53 parts by weight of adipic acid and 0.01 parts by weight of tetraisopropyl orthotitanate are used. An esterification reaction was carried out at 200 to 250 ° C. for 12 hours while stirring in a nitrogen stream, so that a saturated polyester resin (6) was obtained. The saturated polyester resin (6) had a number average molecular weight (Mn) of 1,763, a weight average molecular weight (Mw) of 4,028, an acid value of 4.5 mg KOH / g and a hydroxyl number of 94.4 mg KOH / g.

The obtained saturated polyester resin (6) was dissolved in butyl acetate to obtain a solution of the saturated polyester resin (6) with a non-volatile content of 72% by weight. The Gardner viscosity of the solution of the saturated polyester resin (6) was Z1-Z2.

(Embodiment 1: Preparation of a solution of a (meth) acrylic-modified polyester resin (1))

In a reaction vessel with a stirrer, a condenser and a thermometer, 17.41 parts by weight of the solution of the saturated polyester resin (1) obtained in Preparation Example 1 and 20.38 parts by weight of butyl acetate were placed and heated to 120 to 130 ° C. A (meth) acrylic monomer mixture shown in Table 1, 4.96 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide and 0.5 part by weight of 1-dodecanethiol were then added dropwise over a period of 4 to 6 hours. Next, 0.07 parts by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours so that a solution of a (meth) acrylic-modified polyester resin (1) having a non-volatile content of 70.5 % By weight was obtained. The solution of the (meth) acrylic-modified polyester resin (1) had a number average molecular weight (Mn) of 2,942, a weight average molecular weight (Mw) of 8,468, an acid value of 11 mg KOH / g, a hydroxyl number (solids content) of 141 mg KOH / g and a Gardner viscosity of Z1-Z2.

(Embodiment 2: Preparation of a (meth) acrylic-modified polyester resin (2)) 15.76 parts by weight of the solution of the saturated polyester resin (2) obtained in Preparation Example 2, 5.22 parts by weight of glycidyl odecanoate were placed in a reaction vessel with a stirrer, a condenser and a thermometer and 26.25 parts by weight of butyl acetate and heated to 120 to 130 ° C. Thereafter, over a period of 4 to 6 hours, a (meth) acrylic monomer mixture and 4.02 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide were added dropwise. Next, 0.07 parts by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours so that a solution of a (meth) acrylic-modified polyester resin (2) having a nonvolatile content of 72.3 % By weight was obtained. The solution of the (meth) acrylic modified polyester resin (2) had a number average molecular weight (Mn) of 2,593, a weight average molecular weight (Mw) of 6,660, an acid value of 15.2 mg KOH / g, a hydroxyl number (solids content) of 143 mg KOH / g and a Gardner viscosity of Z4-Z5.

(Embodiment 3: Production of a (meth) acrylic-modified polyester resin (3)) In a reaction container with a stirrer, a condenser and a thermometer, 18.30 parts by weight of the solution of the saturated polyester resin (3) obtained in Preparation Example 3 and 21.26 parts by weight of butyl acetate were used and heated to 120 to 130 ° C. A (meth) acrylic monomer mixture shown in Table 1, 4.89 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide and 0.5 part by weight of 1-dodecanethiol were then added dropwise over a period of 4 to 6 hours. Next, 0.07 parts by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours so that a (meth) acrylic-modified polyester resin (3) having a nonvolatile content of 76.5 parts by weight. -% was received. The solution of the (meth) acrylic modified polyester resin (3) had a number average molecular weight (Mn) of 2,363, a weight average molecular weight (Mw) of 6,873, an acid value of 11.2 mg KOH / g, a hydroxyl number (solids content) of 140 mg KOH / g and a Gardner viscosity of Z - Z1.

(Embodiment 4: Preparation of a (meth) acrylic-modified polyester resin (4)) 22.05 parts by weight of the solution of the saturated polyester resin (4) obtained in Preparation Example 4, 12.88 parts by weight of butyl acetate were placed in a reaction container with a stirrer, a condenser and a thermometer and 19.24 parts by weight of propylene glycol monomethyl ether acetate and heated to 120 to 130 ° C. A (meth) acrylic monomer mixture shown in Table 1, 3.15 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide and 0.45 parts by weight of 1-dodecanethiol were then added dropwise over a period of 4 to 6 hours. Next, 0.06 parts by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours so that a solution of a (meth) acrylic-modified polyester resin (4) having a non-volatile content of 65 parts by weight. -% was received. The solution of the (meth) acrylic-modified polyester resin (4) had a number average molecular weight (Mn) of 3,172, a weight average molecular weight (Mw) of 8,126, an acid value of 7.5 mg KOH / g, a hydroxyl number (solids content) of 77.4 mg KOH / g and a Gardner viscosity of L.

(Embodiment 5: Production of a (meth) acrylic-modified polyester resin (5)) 25.25 parts by weight of the solution of the saturated polyester resin (5) obtained in Preparation Example 5, 17.04 parts by weight of butyl acetate were placed in a reaction vessel with a stirrer, a condenser and a thermometer and 3.01 parts by weight of propylene glycol monomethyl ether acetate and heated to 120 to 130 ° C. A (meth) acrylic monomer mixture shown in Table 1, 3.94 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide and 0.54 parts by weight of 1-dodecanethiol were then added dropwise over a period of 4 to 6 hours. Next, 0.07 parts by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours so that a solution of a (meth) acrylic modified polyester resin (5) having a nonvolatile content of 73.7 % By weight was obtained. The solution of the (meth) acrylic-modified polyester resin (5) had a number average molecular weight (Mn) of 2,144, a weight average molecular weight (Mw) of 7,441, an acid value of 7.4 mg KOH / g, a hydroxyl number (solids content) of 80.6 mg KOH / g and a Gardner viscosity of VW.

The compositions of the (meth) acrylic-modified polyester resins (1) to (5) obtained in Examples 1 to 5 are shown in Table 1.

(Comparative Production Example 1: Production of an Acrylic Resin Solution (C1-1))

Butyl acetate was placed in a reaction vessel with a stirrer, a condenser and a thermometer and heated to 120 to 130 ° C. Thereafter, the acrylic monomer mixture used in embodiment 5 was added dropwise over a period of 4 to 6 hours. Next, tert-butylbenzoyl peroxide was added and the mixture was kept at 120 to 130 ° C for 2 hours was left so that an acrylic resin solution (C1-1) with a non-volatile content of 70.8% by weight was obtained. The acrylic resin solution (C1-1) had a number average molecular weight (Mn) of 2,742, a weight average molecular weight (Mw) of 7,841, an acid value of 6.6 mg KOH / g, a hydroxyl number (solids content) of 73.3 mg KOH / g and a Gardner viscosity of Y - Z.

(Comparative Example 1: Preparation of a Mixed Solution (C1) from an Acrylic Resin and a Polyester Resin)

The acrylic resin solution (C1-1) obtained in Comparative Production Example 1 and the solution of the saturated polyester resin (5) obtained in Production Example 5 were mixed at 25 ° C. in such a way that the same amount of polyester as in Example 5 was obtained, so that a mixed solution (C1) was obtained an acrylic resin and a polyester resin was obtained.

(Comparative Example 2: Preparation of a (Meth) Acrylic-Modified Polyester Resin (C2)) In a reaction vessel with a stirrer, a condenser and a thermometer, 46.7 parts by weight of the solution of the saturated polyester resin (6) obtained in Preparation Example 6, 1.41 parts by weight of butyl acetate and 12.7 parts by weight of propylene glycol monomethyl ether acetate and heated to 120 to 130 ° C. A (meth) acrylic monomer mixture shown in Table 2, 2.39 parts by weight of (2-ethylhexanoyl) (tert-butyl) peroxide and 0.27 part by weight of 1-dodecanethiol were then added dropwise over a period of 4 to 6 hours. Next, 0.05 part by weight of tert-butylbenzoyl peroxide was added, and the mixture was allowed to stand at 120 to 130 ° C for 2 hours. However, the solution was separated into two layers so that no targeted (meth) acrylic modified polyester resin solution was obtained.

(Embodiment 6: Production of a White Lacquer (1))

In a reaction vessel with a stirrer, a condenser and a thermometer, 26.4 parts by weight of the solution of the (meth) acrylic-modified polyester resin (4) obtained in embodiment 4, 34.3 parts by weight of titanium oxide (“Ti-Pure R 960” manufactured by DuPont) were , 0.3 parts by weight of silica ("Aerosil R 972" manufactured by Evonik Industries) and 4.1 parts by weight of mixed solvent, obtainable by mixing an aromatic-based solvent ("Solvesso 100" manufactured by ExxonMobil YK) with a propylene glycol monomethyl ether acetate in a weight ratio of 7 : 3, mixed and dispersion was carried out until the particle diameter became 10 µm or smaller. Thereafter, 26.4 parts by weight of the solution of the (meth) acrylic-modified polyester resin (4), 6.1 parts by weight of amino resin ("Cymel 303LF" manufactured by Allnex), 0.6 parts by weight of a catalyst ("Nacure 5225" manufactured by King Industries) , Inc.), 0.3 part by weight of matting agent ("Syloid ED3", manufactured by Allnex), 0.5 part by weight of leveling agent ("Modaflow 2100", manufactured by Allnex) and 1.0 part by weight of mixed solvent, obtainable by mixing a solvent based of aromatics ("Solvesso 100", manufactured by ExxonMobil YK) with a propylene glycol monomethyl ether acetate in a weight ratio of 7: 3, added, mixed and further adjusted so that the viscosity of the Ford cup No. 4 at 25 ° C for about 100 seconds to obtain a white varnish (1).

(Embodiment 7: Production of a White Lacquer (2))

A white lacquer (2) was obtained analogously to embodiment 6, with the exception that, as a replacement for the solution of the (meth) acrylic-modified polyester resin (4) used in embodiment 6, the solution of the (meth) acrylic-modified polyester resin (5) obtained in embodiment 5 has been used.

(Comparative Example 3: Production of a White Lacquer (3))

A white lacquer (3) was obtained analogously to embodiment 6, with the exception that, as a replacement for the solution of the (meth) acrylic-modified polyester resin (4) used in embodiment 6, the mixed solution (C1) obtained from comparative example 1, comprising the acrylic resin and the polyester resin has been used.

(Comparative Example 4: Production of a White Lacquer (4))

A white lacquer (4) was obtained analogously to exemplary embodiment 6, with the exception that a solution of a saturated polyester resin (“BECKOLITE GS-13”, manufactured by. As a replacement for the solution of the (meth) acrylic-modified polyester resin (4) used in exemplary embodiment 6 DIC Corporation) was used.

(Comparative Example 5: Production of a White Lacquer (5))

A white lacquer (5) was obtained analogously to exemplary embodiment 6, with the exception that a solution of a saturated polyester resin (“BECKOLITE GS-37-1”), as a replacement for the solution of the (meth) acrylic-modified polyester resin (4) used in exemplary embodiment 6. manufactured by DIC Corporation) was used.

(Comparative Example 6: Production of a White Lacquer (6))

A white lacquer (6) was obtained analogously to embodiment 6, with the exception that the acrylic resin solution (C1-1) obtained in comparative preparation example 1 was used as a substitute for the solution of the (meth) acrylic-modified polyester resin (4) used in embodiment 6.

(Comparative Example 7: Production of a White Lacquer (7))

A white lacquer (7) was obtained analogously to exemplary embodiment 6, with the exception that a solution of a saturated polyester resin (“BECKOLITE GS-12”, manufactured by. As a replacement for the solution of the (meth) acrylic-modified polyester resin (4) used in exemplary embodiment 6 DIC Corporation) was used.

Lacquered steel sheets were produced using the white lacquers obtained in the above exemplary and comparative examples.

(Examples 8 and 9: Production of the painted steel sheets (A) and (B))

The hot-dip galvanized, chromate-treated steel sheets with a thickness of 0.5 mm were coated with the white varnishes (1) and (2) obtained in working examples 5 and 6 using a bar coater in such a way that the film thickness was 15 to 20 µm amounted to. These were then heated in an oven at 250 ° C for 20 seconds and dried (metal tip temperature: 210 ° C), so that the painted steel sheets (A) and (B) were obtained.

(Comparative Examples 8 to 11: Production of the Painted Steel Sheets (C) to (F))

On hot-dip galvanized, chromate-treated steel sheets with a thickness of 0.5 mm, the white lacquers (3) to (6) obtained in Comparative Examples 3 to 6 were each coated using a bar coater in such a way that the film thickness was 15 to 20 μm. These were then heated in an oven at 230 ° C for 40 seconds and dried (metal tip temperature: 230 ° C), so that the painted steel sheets (C) to (F) were obtained.

(Examples 10 and 11: Production of the painted steel sheets (G) and (H) <with primer layer>)

As such, a primer layer was formed by painting a saturated polyester resin ("BECKOLITE GS-12", manufactured by DIC Corporation) on hot-dip galvanized, chromate-treated steel sheets with a thickness of 0.5 mm by means of a bar coater so that the film thickness 5 µm was. This was then heated in an oven at 250 ° C for 20 seconds and dried (metal tip temperature: 210 ° C). Next, the white lacquers (1) and (2) obtained in the exemplary embodiments 5 and 6 were coated onto the respective surface of the primer layer by means of a bar coater such that the film thickness was 15 μm. These were then heated in an oven at 250 ° C for 40 seconds and dried (metal tip temperature: 210 ° C), so that the painted steel sheets (G) and (H) were produced.

(Comparative Examples 12 to 14: Production of the Painted Steel Sheets (I) to (K) <with Primer Layer))

As such, a primer layer was formed by painting a saturated polyester resin ("BECKOLITE GS-12", manufactured by DIC Corporation) on hot-dip galvanized, chromate-treated steel sheets with a thickness of 0.5 mm by means of a bar coater so that the film thickness 5 µm was. These were then heated in an oven at 250 ° C for 20 seconds and dried (metal tip temperature: 210 ° C). Next, the white paints (3), (6) and (7) obtained in Comparative Examples 3, 6 and 7 were coated on the respective surface of the undercoat layer by means of a bar coater such that the film thickness was 15 µm. These were then heated in an oven at 250 ° C for 40 seconds and dried (metal tip temperature: 230 ° C), so that the painted steel sheets (I) to (K) were produced.

The following evaluations were made using the painted steel sheets obtained in the above embodiment and comparative examples.

[Measurement method of pencil hardness]

The hardness of the painted surfaces of the painted steel sheets (A) to (K) was measured using the method according to EN 13523-4.

[Measurement method of gloss]

The gloss of the painted surfaces of the painted steel sheets (A) to (K) was measured for its reflectance at an angle of 60 ° according to the method according to EN 13523-2.

[Evaluation method of workability (test for freedom from cracks)]

The flexibility of the paint films was assessed by the T-bending test. Specifically, the painted steel sheets (A) to (K) obtained above were bent by 180 ° in accordance with EN 13523-7 and the cracks which were produced in the bent part were observed with a 10-times magnifying glass. The case in which the painted steel sheets were bent by 180 ° without pinching anything in the bent part was called 0T, and the case in which the painted steel sheets were bent, with X plates having the same thickness as that painted steel sheets were pinched in the bent part was given as (X / 2) T. It was rated with a minimum value without cracking in the bent part.

Machinability Assessment Method (Band Test)

The flexibility of the paint films was assessed by the T-bending test. Specifically, according to EN 13523-7, the painted steel sheets (A) to (K) obtained above were bent by 180 ° and an adhesive tape manufactured by NICHIBAN Co., Ltd. was stuck on the bent part. It was then evaluated whether peeling of the paint films occurred when the tape was peeled off quickly. The case where the painted steel sheets were bent 180 ° without pinching anything in the bent part was called 0T, and the case where the painted steel sheets were bent, with X plates having the same thickness as the painted steel sheets in the bent Partially pinched was given as (X / 2) T. It was rated with a minimum value without formation of a transfer.

[Weather Resistance Assessment Method]

A weather resistance test was carried out using the "QUV Accelerated Weathering Tester" manufactured by Q-Lab. Specifically, the painted steel sheets (A) to (K) obtained above were kept at 60 ° C for 4 hours while being subjected to UV irradiation (UV-A lamp), and then a 2000-hour weather resistance test was carried out at 50 ° C with a cycle of 4 hours under moist conditions. It was evaluated based on the glossiness of the paint film surface.

[Pollution Resistance Assessment Method]

1. A: Es verbleiben keine Spuren auf der Oberfläche der lackierten Stahlbleche
2. B: Es verbleiben leichte Spuren auf der Oberfläche der lackierten Stahlbleche
3. C: Es verbleiben Spuren auf der Oberfläche der lackierten Stahlbleche

About 2 ml of a 10% aqueous carbon black dispersion was dropped on the painted steel sheets (A) to (K) obtained above, they were dried at 80 ° C for 24 hours, then wiped with a pad soaked in water, and according to the following Criteria evaluated.

1. A: There are no traces on the surface of the painted steel sheets
2. B: There are slight traces on the surface of the painted steel sheets
3. C: There are traces on the surface of the painted steel sheets

The evaluation results of the painted steel sheets (A) to (F) produced in working examples 8 and 9 and comparative examples 8 to 11 are given in Table 3.

The evaluation results of the painted steel sheets (G) to (K) produced in working examples 10 and 11 and comparative examples 12 to 14 are given in Table 4.

(Embodiment 12: production of a clear lacquer (1))

In a reaction container with a stirrer, a condenser and a thermometer, 87.8 parts by weight of the solution of the (meth) acrylic-modified polyester resin (5) obtained in Example 5, 10.0 parts by weight of amino resin (“Cymel 303 LF” manufactured by Allnex), 0 , 9 parts by weight of a catalyst ("Nacure 5225" manufactured by King Industries, Inc.), 0.5 part by weight of leveling agent ("Modaflow 2100" manufactured by Allnex) and 0.8 part by weight of mixed solvent, obtainable by mixing a solvent based on aromatics ("Solvesso 100", manufactured by ExxonMobil YK) with a propylene glycol monomethyl ether acetate in a weight ratio of 7: 3, added, mixed and further adjusted such that the viscosity of the Ford cup No. 4 at 25 ° C. was about 100 seconds, to get a clear coat (1).

(Example 13: Production of a painted steel sheet (L))

The clear lacquer (1) obtained in exemplary embodiment 12 was coated on a hot-dip galvanized, chromate-treated steel sheet with a thickness of 0.5 mm in such a way that the film thickness was 15 to 20 μm. This was then heated in an oven at 250 ° C for 20 seconds and dried (metal tip temperature: 210 ° C), so that a painted steel sheet (L) was obtained.

Embodiments 8 and 9 shown in Table 3 are examples of white paints using the (meth) acrylic modified polyester resin of the present invention. The two white lacquers each had a high non-volatile content of 73.3% by weight. It was therefore found that a high-strength paint can be produced. It was also found that the lacquer films of the white lacquers were not only distinguished by excellent workability and weather resistance, but also by lacquer film hardness and dirt resistance.

In contrast, Comparative Example 8 is an example of a white paint using a mixed solution of an acrylic resin and a polyester resin. The white paint had a high non-volatile content, so a high-strength paint can be produced. However, it was found that the paint film of the paint had a low gloss retention of 60%, so that the weather resistance was inadequate.

Comparative Examples 9 and 10 are examples of white paints using a saturated polyester resin. The non-volatile content was 64.3% by weight (Comparative Example 9) and 63.2% by weight (Comparative Example 10), respectively, so that it was low. It was therefore determined that a high-strength varnish cannot be produced. In addition, it was found that the paint films of the white paints each had an extremely low gloss retention of 30% (Comparative Example 9) and 55% (Comparative Example 10), so that the weather resistance was extremely inadequate.

Comparative Example 11 is an example of a white paint using an acrylic resin solution. The white paint had a high non-volatile content, so a high-strength paint can be produced. However, it was found that the workability of the paint film of the paint was insufficient.

The exemplary embodiments 10 and 11 shown in Table 4 and the comparative examples 12 to 14 relate to the respective painted steel sheet, in which a primer layer is provided between the steel sheet and the white paint. It was found that the paint films of the white paints on the painted steel sheets obtained in working examples 10 and 11 were not only distinguished by excellent workability and weather resistance, but also by paint film hardness and dirt resistance.

Embodiment 13 shown in Table 5 is an example of a clear coat using the (meth) acrylic modified polyester resin of the present invention. It was found that the lacquer film of the clear lacquer on the lacquered steel sheet obtained in exemplary embodiment 13 was distinguished not only by excellent workability and weather resistance, but also by lacquer film hardness and dirt resistance.

Claims (10)

(Meth) acrylic-modified polyester resin, in which a saturated polyester resin (A) and a (meth) acrylic monomer mixture (B) comprising a hydroxyl group-containing (meth) acrylic monomer are used as required raw materials, characterized in that the saturated polyester resin (A) is a polycondensate of an aliphatic diol (a1) and a dicarboxylic acid (a2) comprising an aliphatic dicarboxylic acid, the content of the aliphatic dicarboxylic acid being 5% by weight or more in the dicarboxylic acid (a2). (Meth) acrylic modified polyester resin according to Claim 1 , wherein the weight ratio [(A) / (B)] of the saturated polyester resin (A) to the (meth) acrylic monomer mixture (B) is in the range from 15/85 to 50/50. (Meth) acrylic modified polyester resin according to Claim 1 or 2nd , wherein the aliphatic diol (a1) contains an asymmetric diol with at least one side chain and / or a linear diol without side chains. (Meth) acrylic modified polyester resin according to one of the Claims 1 to 3rd , wherein the weight average molecular weight of the saturated polyester resin (A) is in the range of 1,000 to 5,000. (Meth) acrylic modified polyester resin according to one of the Claims 1 to 4th wherein the (meth) acrylic monomer mixture (B) comprises 10% by weight or more of the hydroxyl group-containing (meth) acrylic monomer. (Meth) acrylic modified polyester resin according to one of the Claims 1 to 5 , wherein the weight average molecular weight of the (meth) acrylic-modified polyester resin is in the range of 5,000 to 20,000. (Meth) acrylic modified polyester resin according to one of the Claims 1 to 6 , wherein the hydroxyl number of the (meth) acrylic-modified polyester resin is in the range from 60 to 150. Curable resin composition, characterized in that it contains the (meth) acrylic modified polyester resin according to one of the Claims 1 to 7 and comprises a curing agent. Lacquer, characterized in that it according to the curable resin composition Claim 8 consists. Painted steel sheet, characterized in that there is a hardened paint film according to the paint Claim 9 having.