CN113227280A

CN113227280A - Varnish composition

Info

Publication number: CN113227280A
Application number: CN201980086752.5A
Authority: CN
Inventors: 金孟岐; 郑善化; 崔明基; 邢宇粲; 金昌赫; 文晟僖
Original assignee: KCC Corp
Current assignee: KCC Corp
Priority date: 2018-12-31
Filing date: 2019-12-03
Publication date: 2021-08-06
Anticipated expiration: 2039-12-03
Also published as: WO2020141733A1; KR20200082837A; KR102242958B1; CN113227280B; SG11202106801WA

Abstract

The present invention relates to a varnish composition comprising a silicone-modified polyester polyol resin, an acrylic polyol resin, a polyester resin, and an isocyanate resin.

Description

Varnish composition

Technical Field

The present invention relates to a varnish composition.

Background

Generally, an outer panel of a vehicle body is required to prevent deterioration and rusting of a coating film and to have durability to maintain gloss or color of the coating film. Therefore, the coating process of automobiles is generally performed by electrodeposition coating of vehicle bodies that have undergone a pretreatment process, i.e., primer coating for improving adhesion and smoothness, and finish coating of vehicle bodies that have undergone primer coating for the appearance of the vehicle bodies. Thereafter, a clear coat film is usually applied to protect the color of the top coat film and to improve the appearance of the top coat film, and to protect the top coat film from external influences.

As a conventional varnish for vehicles, thermosetting coating compositions of hydroxyl group-containing resins and amino resins are widely used. However, in the case of using a conventional thermosetting coating composition, the appearance of parts composed of plastic materials, such as a bumper and a rearview mirror assembly, may be changed or distorted during curing under high-temperature curing conditions, and the parts need to be separated to separately perform a coating process, which is inconvenient. Further, there is a disadvantage in that the color of the part of the plastic material, which is separated from the vehicle body and separately coated, becomes different from the color of the vehicle body itself. Therefore, a low-temperature curable varnish composition has been attracting attention, which lowers the curing temperature for integral coating of parts of plastic materials bonded to vehicle bodies.

Alternatively, korean registered patent No. 1,655,621 (patent document 1) discloses a varnish composition including two types of acrylic polyol resins, polyester polyol resins, reactive silicone additives, and isocyanate curing agents. However, the conventional low-temperature curable varnish composition such as the varnish composition of patent document 1 makes the mechanical properties of the coating film formed therefrom insufficient and can be used only for repair or coating of parts, with limitations in use for vehicle body coating.

Therefore, research and development of a varnish composition that can be cured at a low temperature of 120 ℃ or less than 120 ℃, can provide a coating film having excellent mechanical properties, and can be suitably used for coating a vehicle body are required.

Disclosure of Invention

Technical problem

Accordingly, the present invention provides a varnish composition which is curable at a low temperature of 120 ℃ or less than 120 ℃ and is capable of producing a coating film having excellent mechanical properties.

Technical scheme

The present invention provides a varnish composition comprising a silicone-modified polyester polyol resin, an acrylic polyol resin, a polyester resin, and an isocyanate resin.

Advantageous effects

The varnish composition according to the present invention is curable at a low temperature of 120 ℃ or less than 120 ℃, can save costs required during a coating process and is economical, and can integrally coat a vehicle body and material parts combined therewith, and therefore, defects regarding different colors of the coated parts and the vehicle body can be prevented. Further, since both the vehicle body and the parts can be coated by one coating process, inconvenience and cost loss associated with the process can be eliminated. Further, a coating film formed from the varnish composition has excellent mechanical properties such as hardness, adhesion, water resistance, acid resistance, scratch resistance and solvent resistance, and is useful for coating a vehicle body.

Detailed Description

The varnish composition according to the present invention contains a silicone-modified polyester polyol resin, an acrylic polyol resin, a polyester resin, and an isocyanate resin.

Silicone-modified polyester polyol resins

The silicone-modified polyester polyol resin functions to improve scratch resistance of a coating film formed from a composition containing the same.

The silicone-modified polyester polyol resin may include a first repeating unit derived from an organopolysiloxane, a second repeating unit derived from a polyfunctional alcohol, and a third repeating unit derived from a polyfunctional carboxylic acid. For example, the silicone-modified polyester polyol resin may be composed of a first repeating unit derived from an organopolysiloxane, a second repeating unit derived from a polyfunctional alcohol, and a third repeating unit derived from a polyfunctional carboxylic acid. That is, the silicone-modified polyester polyol resin may be prepared by the reaction of an organopolysiloxane, a polyfunctional alcohol monomer, and a polyfunctional carboxylic acid monomer. In another embodiment, the silicone-modified polyester polyol resin may be prepared by a condensation reaction of an organopolysiloxane, a polyfunctional alcohol monomer, and a polyfunctional carboxylic acid monomer.

The organopolysiloxane may comprise functional groups and non-functional organic groups. For example, the organopolysiloxane may comprise one or more functional groups selected from silanol and alkoxy groups, and one or more non-functional groups selected from methyl, propyl, and phenyl groups. Alkoxy groups may include, for example, methoxy, ethoxy, and butoxy.

The organopolysiloxane may have a number average molecular weight of 100g/mol to 5,000 g/mol. For example, the organopolysiloxane can have a number average molecular weight of 200g/mol to 5,000g/mol, 300g/mol to 5,000g/mol, or 500g/mol to 5,000 g/mol.

Organopolysiloxanes can include commercially available products including DC-3037, DC-3074, RSN-0217, RSN-0220, RSN-0233, RSN-0255, and RSN-6018 from Dow Corning Co., and SY300, IC836, REN168, SY409, IC232, SY231, IC368, IC678, 601, 603, and 604 from the SILRES series of Wacker Co.

The polyfunctional alcohol monomer may be, for example, one or more selected from the group consisting of Ethylene Glycol (EG), Propylene Glycol (PG), Trimethylolpropane (TMP), Trimethylolethane (TME), cyclohexanedimethanol, neopentyl glycol (NPG), 2-butyl-2-ethyl-1, 3-propanediol, 1, 6-hexanediol, diethylene glycol, dipropylene glycol, tripropylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, trimethylolpropane, glycerol, and pentaerythritol.

The polyfunctional carboxylic acid monomer may be, for example, one or more selected from Phthalic Anhydride (PA), hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, succinic anhydride, isophthalic acid, azelaic acid, maleic anhydride, and trimellitic anhydride.

The silicone-modified polyester polyol resin may be prepared by the reaction of 100 parts by weight of an organopolysiloxane, 300 to 800 parts by weight of a polyfunctional alcohol monomer, and 300 to 600 parts by weight of a polyfunctional carboxylic acid monomer. For example, the silicone-modified polyester polyol resin may be prepared by the reaction of 100 parts by weight of an organopolysiloxane, 400 to 700 parts by weight or 500 to 650 parts by weight of a polyfunctional alcohol monomer, and 350 to 550 parts by weight or 400 to 500 parts by weight of a polyfunctional carboxylic acid monomer. In the case of preparing the silicone-modified polyester polyol resin by using the monomers in the above amount range, the effect of improving the appearance characteristics and scratch resistance of the coating film formed from the coating composition comprising the above monomers can be achieved.

The silicone-modified polyester polyol resin may have a hydroxyl value (OHV) of 150 to 350mg KOH/g, an acid value (Av) of greater than 0mg KOH/g and 30mg KOH/g or less, a number average molecular weight (Mn) of 100 to 10,000g/mol, and a glass transition temperature (Tg) of-50 to 30 ℃. For example, the silicone-modified polyester polyol resin can have a hydroxyl value of 150 to 300mg KOH/g or 200 to 300mg KOH/g, an acid value of 1 to 30mg KOH/g or 1 to 20mg KOH/g, a number average molecular weight of 100 to 5,000g/mol or 100 to 2,000g/mol, and a glass transition temperature of-30 to 30 ℃ or greater than 0 ℃ and 20 ℃ or less.

In the case where the hydroxyl value of the silicone-modified polyester polyol resin is within the above range, curability can be improved, in the case where the acid value is within the above range, reactivity can be controlled and appearance characteristics can be improved, in the case where the number average molecular weight is within the above range, a coating film having excellent appearance characteristics can be formed, and in the case where the glass transition temperature is within the above range, appearance characteristics of the coating film can be improved and a satisfactory effect of a coating Solid Volume Ratio (SVR) can be achieved.

The silicone-modified polyester polyol resin may be included in an amount of 1 to 30 parts by weight, based on 1 to 30 parts by weight of the acrylic polyol resin. For example, the silicone-modified polyester polyol resin may be included in an amount of 5 to 20 parts by weight or 5 to 15 parts by weight, based on 1 to 30 parts by weight of the acrylic polyol resin. If the amount of the silicone-modified polyester polyol resin is within the above range, it is possible to prevent the defect of deterioration in the glossiness of a coating film formed from a coating composition containing the silicone-modified polyester polyol resin, and the defect of deterioration in the appearance characteristics and curing density of the coating film.

Acrylic polyol resin

The acrylic polyol resin functions to provide the composition with the property of forming a coating film.

The acrylic polyol resin may include repeating units derived from an ethylenically unsaturated monomer and repeating units derived from a hydroxyl group-containing acrylic monomer. That is, the acrylic polyol resin may be prepared by the reaction of an ethylenically unsaturated monomer and a hydroxyl group-containing acrylic monomer. For example, the acrylic polyol resin may be prepared by the reaction of an ethylenically unsaturated monomer, a hydroxyl group-containing acrylic monomer, and a radical polymerization initiator in a solvent. In another embodiment, the acrylic polyol resin may be prepared by the reaction of an ethylenically unsaturated monomer, a hydroxyl group-containing acrylic monomer, a non-functional acrylic monomer, a free radical polymerization initiator, and a molecular weight controlling agent in a solvent.

The ethylenically unsaturated monomer may be chosen from styrene and its derivatives, butadiene, C_1-12Alkyl (meth) acryloyl and C_1-12One or more alkyl (meth) acrylates.

The hydroxyl group-containing acrylic monomer may be one or more selected from the group consisting of hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, cardura methacrylate, caprolactone acrylate, caprolactone methacrylate, 2, 3-dihydroxypropyl acrylate, 2, 3-dihydroxypropyl methacrylate, polypropylene-modified acrylates, polypropylene-modified methacrylates, 4-hydroxymethylcyclohexylmethyl acrylate, 4-hydroxymethylcyclomethyl methacrylate and ethylenically unsaturated beta-hydroxy esters.

Ethylenically unsaturated beta-hydroxy esters can be prepared by the reaction of an ethylenically unsaturated acid monomer and an epoxy compound. The ethylenically unsaturated acid monomer may be, for example, a monocarboxylic acid, such as (meth) acrylic acid. In addition, the epoxy compound does not participate in radical polymerization, and may include, for example, glycidyl ethers and glycidyl esters.

The non-functional acrylic monomer may include one or more selected from the group consisting of alkyl (meth) acrylate, cycloalkyl (meth) acrylate, and bicycloalkyl (meth) acrylate. For example, the non-functional acrylic monomer may be one or more selected from the group consisting of methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, 2-ethylhexyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, n-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isobornyl acrylate, and cyclohexyl acrylate.

The solvent may use a common solvent during radical polymerization without particular limitation, and may include, for example, aromatic hydrocarbon-based solvents such as toluene and xylene; ketone-based solvents such as methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, and ethyl propyl ketone; ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, and ethyl ethoxypropionate; and alcohol-based solvents such as n-butanol, propanol, and 1-methoxy-2-propanol.

Further, the aromatic hydrocarbon-based solvent may include KOKOSOL #100, KOKOSOL #150, and the like, which are commercially available products.

The radical polymerization initiator may use any polymerization initiator commonly used during radical polymerization without particular limitation, and may include, for example, one or more selected from 2,2 '-azobis (2-methylbutyronitrile), 2' -azobisisobutyronitrile, dibenzoyl peroxide, tert-butyl peroxybenzoate, di-tert-butyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyacetate, tert-amyl peroxy-2-ethylhexanoate, di-tert-amyl peroxide, cumyl hydroperoxide, and dicumyl peroxide.

The molecular weight controlling agent may use a general molecular weight controlling agent used for preparing the acrylic polyol without particular limitation, and may include, for example, mercaptans such as n-dodecylmercaptan, n-decylthiol and t-dodecylmercaptan; and alpha methyl styrene dimer.

The acrylic polyol resin can have a hydroxyl value of 80mg KOH/g to 200mg KOH/g, an acid value greater than 0mg KOH/g and less than 30mg KOH/g, a number average molecular weight of 1,000g/mol to 10,000g/mol, and a glass transition temperature greater than 0 ℃ and less than 70 ℃. In another embodiment, the acrylic polyol resin may have a hydroxyl value of 100 to 200mg KOH/g, an acid value of 1 to 25mg KOH/g or 5 to 15mg KOH/g, a number average molecular weight of 1,500 to 7,000g/mol or 2,000 to 5,000g/mol, and a glass transition temperature of 10 to 70 ℃ or 20 to 60 ℃.

In the case where the hydroxyl value of the acrylic polyol resin is within the above range, curability of the composition comprising the acrylic polyol resin may be improved, in the case where the acid value is within the above range, reactivity of the composition comprising the acrylic polyol resin may be controlled, and appearance characteristics of a coating film formed therefrom may be improved, in the case where the number average molecular weight is within the above range, appearance characteristics and physical properties of the formed coating film may be suitable, and in the case where the glass transition temperature is within the above range, initial hardness of the formed coating film may be improved.

The acrylic polyol resin may be included in an amount of 1 to 30 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. For example, the acrylic polyol resin may be included in an amount of 5 to 20 parts by weight or 5 to 15 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. If the amount of the acrylic polyol resin is within the above range, it is possible to prevent the defect of deterioration in glossiness of a coating film formed from a coating composition comprising the acrylic polyol resin, and the defect of deterioration in appearance characteristics and curing density of the coating film.

Polyester resin

The polyester resin functions to improve the curing rate of a composition containing the same.

The polyester resin may be a polyester resin directly synthesized according to a known method or a commercially available product may be used. For example, the polyester resin may be prepared by reacting a carboxylic acid with a polyol.

In this case, the carboxylic acid may be one or more selected from Adipic Acid (AA), isophthalic acid (IPA), phthalic anhydride (TMA), hexahydrophthalic anhydride (HHPA), alicyclic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, fumaric acid, maleic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and derivatives thereof. Further, the polyol may be one or more selected from methoxypolyethylene glycol, neopentyl glycol (NPG), Trimethylolpropane (TMP), 1, 6-hexanediol (1,6-HD), ethylene glycol, propylene glycol, diethylene glycol, butanediol, 1, 4-hexanediol, and 3-methylpentanediol.

Further, the polyester resin may have a liquid phase type having a solid content (NV) of 50 to 90 wt% based on the total weight of the resin. In another embodiment, the polyester resin may have a liquid phase type having a solid content (NV) of 50 wt% to 80 wt%, or 60 wt% to 75 wt%, based on the total weight of the resin. If the polyester resin is used in a liquid phase type, advantageous effects of processability and leveling of the composition can be achieved, and if a liquid phase type polyester resin having a solid content within the above-mentioned range is used, the content of organic volatile compounds (VOC) in the composition can be reduced, and an effect of improving eco-friendliness can be achieved.

Further, the polyester resin may have an acid value (Av) of 1 to 30mgKOH/g and a hydroxyl value (OHV) of 100 to 400 mgKOH/g. In another embodiment, the polyester resin may have an acid value of 10 to 30mg KOH/g, or 15 to 25mg KOH/g, and a hydroxyl value of 150 to 350mg KOH/g, or 200 to 320mg KOH/g. If the acid value of the polyester resin is within the above range, the water resistance of the formed coating film can be improved, and if the hydroxyl value is within the above range, the effect of improving chemical resistance and mechanical properties can be achieved.

Further, the polyester resin may have a number average molecular weight (Mn) of 100g/mol to 700 g/mol. For example, the polyester resin can have a number average molecular weight of 200g/mol to 600g/mol, or 250g/mol to 500 g/mol. If the number average molecular weight of the polyester resin is within the above range, an excellent effect of curing density can be achieved.

Further, the polyester resin may be included in the composition in an amount of 5 to 40 parts by weight, relative to 1 to 30 parts by weight of the silicone-modified polyester polyol resin. For example, the polyester resin may be included in the composition in an amount of 10 to 30 parts by weight or 15 to 25 parts by weight, relative to 1 to 30 parts by weight of the silicone-modified polyester polyol resin. If the amount of the polyester resin is within the above range, the appearance and chipping properties of the formed cured film may be excellent, and an excellent curing effect at a low temperature of 120 ℃ or less may be achieved.

Isocyanate resin

The isocyanate resin functions to cure the composition by a crosslinking reaction with the components in the composition to form a coating film.

The isocyanate resin may comprise one or more functional groups selected from isocyanurate groups, uretdione groups, biuret groups, urethane groups, allophanate groups and iminooxadiazinedione groups. That is, the isocyanate resin may be an isocyanate containing one or more functional groups selected from an isocyanurate group, a uretdione group, a biuret group, a urethane group, an allophanate group and an iminooxadiazinedione group.

The isocyanate resin may be prepared from an aliphatic isocyanate or a cycloaliphatic isocyanate. For example, the isocyanate resin may be formed from an aliphatic isocyanate such as 1, 6-hexamethylene isocyanate; and alicyclic isocyanates such as 1-isocyanato-3-isocyanatomethyl-3, 5, 5-trimethyl-cyclohexane (isophorone diisocyanate, IPDI), bis- (4-isocyanatocyclohexyl) -methane, 1-isocyanato-1-methyl-4 (3) -isocyanatomethylcyclohexane, 2, 4-hexahydrotolylene diisocyanate and 2, 6-hexahydrotolylene diisocyanate. For example, the isocyanate resin may be prepared from one or more isocyanates selected from the group consisting of 1, 6-hexamethylene diisocyanate, 1-isocyanato-3-isocyanatomethyl-3, 5, 5-trimethyl-cyclohexane and bis- (4-isocyanatocyclohexyl) -methane.

The isocyanate resin may be included in an amount of 10 to 40 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. For example, the isocyanate resin may be included in an amount of 15 to 35 parts by weight or 20 to 30 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. If the amount of the isocyanate resin is within the above range, it is possible to prevent the defect of deterioration in curing density due to lack of reactivity of the composition and the defect of deterioration in physical properties of the coating film due to generation of unreacted products in the coating film after curing.

Organic solvent

The coating composition may additionally comprise an organic solvent. In this case, the organic solvent serves to improve the processability of the composition by controlling the viscosity of the coating composition.

The organic solvent may include one or more selected from the group consisting of an aromatic solvent, an acetate-based solvent, an alcohol-based solvent, and a propionate-based solvent. For example, the organic solvent may include aromatic solvents such as toluene and xylene; acetate ester-based solvents such as 1-methoxy-2-propyl acetate, methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, dimethyl glutarate, dimethyl succinate, and dimethyl adipate; alcohol-based solvents such as n-butanol, propanol and 1-methoxy-2-propanol; and propionate-based solvents such as ethyl ethoxypropionate. Further, the aromatic solvent may include kosol #100, KOKOSOL #150, and the like, which are commercially available products. Additionally, commercially available products of acetate-based solvents may include Rhodiasolv RPDE, Solvay co.

The organic solvent may be included in an amount of 5 to 60 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. For example, the organic solvent may be included in an amount of 10 to 50 parts by weight or 10 to 45 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. If the amount of the organic solvent is within the above range, an effect of excellent workability during coating of the coating composition containing the solvent can be achieved.

Additive agent

The varnish composition may additionally comprise one or more additives selected from the group consisting of sag control agents, curing catalysts, wetting agents, light stabilizers, uv absorbers, defoamers, surface modifiers and leveling agents.

The additive may be included in an amount of 1 to 40 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin. For example, the additive may be included in an amount of 1 to 35 parts by weight or 1 to 30 parts by weight, based on 1 to 30 parts by weight of the silicone-modified polyester polyol resin.

The sag control agent functions to control sag of the composition to improve processability of the composition. In addition, the sag control agent may include, for example, an acrylic resin having a diurea group. In another embodiment, the sag control agent may be an acrylic polyol resin having a structure including a diurea group having a needle shape and obtained by reacting an alkyl acrylate (e.g., butyl acrylate), or an alkyl methacrylate (e.g., butyl methacrylate) with 1, 6-hexamethylene diisocyanate and benzylamine.

The curing catalyst functions to prevent incomplete curing of the coating composition and to improve the mechanical properties of a coating film formed therefrom. Further, the curing catalyst may be one or more selected from the group consisting of dibutyltin dilaurate, triethylamine, diethylenetriamine, bismuth carboxylate and zirconium chelate.

The wetting agent functions to improve leveling and wetting of a coating film formed from a composition containing the wetting agent, and any one commonly used in coating compositions may be used without particular limitation. For example, the wetting agent may include a silicone acrylate or acetylene alcohol based wetting agent.

The light stabilizer plays a role in improving weather resistance. The light stabilizer may use any light stabilizer commonly used in coating compositions without particular limitation, for example, a hindered amine-based light stabilizer. For example, hindered amine-based light stabilizers may include 2, 4-bis [ N-butyl-N- (1-cyclohexyloxy-2, 2,6, 6-tetramethylpiperidin-4-yl) amino ] -6- (2-hydroxyethylamine) -1,3, 5-triazine, bis (1,2,2,6, 6-pentamethyl-4-piperidinyl) sebacate, and the like.

The ultraviolet absorber functions to absorb ultraviolet rays to prevent discoloration of the coating composition and to prevent swelling, delamination, and loss of gloss of a coating film formed from the coating composition. Further, the ultraviolet absorber may use any ultraviolet absorber commonly used in coating compositions without particular limitation, for example, benzotriazole-based ultraviolet absorbers such as hydroxyphenyl benzotriazoles. Further, Tinuvin 384 of BASF co. which is a commercially available product can be used as the ultraviolet absorber.

The defoaming agent functions to suppress the generation of bubbles during the preparation of the coating composition and to suppress or eliminate the phenomenon of foaming and popping caused during the formation of a coating film. The defoaming agent may use any defoaming agent commonly used in coating compositions without particular limitation. For example, commercially available Products including BYK-011, BYK-015 and BYK-072 from BYK Co., DF-21 from Air Products Co., agitan 281 from Munzing Co., Foamster-324 from San Nopco Co., etc. can be used as the defoaming agent.

The surface modifier plays a role of controlling surface tension after the coating composition is applied and controlling smoothness of the coating layer, and any surface modifier commonly used in coating compositions may be used without particular limitation. For example, the surface modifying agent may be a surfactant, such as a silicone-based surfactant.

The leveling agent functions to provide smoothness to the coating composition and to improve appearance characteristics of a coating film formed therefrom to suppress the generation of orange peel. Further, any leveling agent commonly used in coating compositions can be used without particular limitation.

Two-pack type coating composition

The varnish composition may be a two-part type coating composition comprising a main part and a curing agent part. Thus, the varnish composition may be used after mixing the main part and the curing agent part before application. In this case, the main part may include a silicone-modified polyester polyol resin, an acrylic polyol resin, a polyester resin, and an organic solvent, and the curing agent part may include an isocyanate resin and an organic solvent. The additive may be contained in at least one of the main part or the curing agent.

The varnish composition may have a solids content (NV) of 40 wt% to 70 wt%. For example, the varnish composition may have a solids content of 40 wt% to 65 wt%, for example, a solids content of 45 wt% to 61 wt%. In the case where the varnish composition has a solid content within the above range, the coating workability of the composition can be improved.

The varnish composition may be cured at 60 ℃ to 120 ℃. For example, the varnish composition may be cured at 70 ℃ to 110 ℃ or 80 ℃ to 110 ℃. Since the varnish composition can be cured in the above temperature range, the cost consumed during the coating process can be saved, and this is economical. In addition, the vehicle body and the material member joined thereto can be integrally painted, and defects of different colors between the member and the vehicle body after painting can be prevented. In addition, since the vehicle body and the parts can be coated all at once, inconvenience of the process and cost loss can be solved.

The varnish composition may have a viscosity of 10 seconds to 40 seconds based on a number 4 ford cup. For example, the varnish composition may have a viscosity of 15 seconds to 35 seconds or 20 seconds to 35 seconds based on a number 4 ford cup. In the case where the viscosity of the varnish composition is less than 10 seconds, defects including vertical sagging may occur, and if the viscosity is more than 40 seconds, the viscosity of the composition is high, and therefore, the appearance characteristics of a coating film formed therefrom may be reduced, or a load may be applied to the coater, causing the coater to fail.

The above varnish composition according to the present invention can be cured at a low temperature of 120 ℃ or less than 120 ℃, and saves costs consumed during the coating process, and is economical. In addition, the vehicle body and the material member joined thereto can be integrally painted, and defects of different colors between the member and the vehicle body after painting can be prevented. In addition, since the vehicle body and the parts can be coated all at once, inconvenience of the process and cost loss can be solved. Further, a coating film formed from the varnish composition has excellent mechanical properties such as appearance characteristics, adhesion, water resistance, acid resistance, scratch resistance and solvent resistance, and is useful for coating a vehicle body.

Modes for carrying out the invention

Hereinafter, the present invention will be explained more specifically with reference to embodiments.

However, the embodiments are only for assisting understanding of the present invention, and the scope of the present invention is not limited thereto in any sense.

In the present invention, the functional group values such as "acid value" and "hydroxyl value" of the resin may be measured by methods well known in the art, and for example, may represent values measured by a titration method.

In addition, the "number average molecular weight" of the resin may be measured by a method well known in the art, for example, may represent a value measured by a Gel Permeation Chromatography (GPC) method.

In addition, the "glass transition temperature" of the resin may be measured by a method well known in the art, and for example, may represent a value measured by a Differential Scanning Calorimetry (DSC) method.

Synthesis example 1: preparation of Silicone-modified polyester polyol resins

Into a four-necked flask equipped with a thermometer, a stirring device, a condenser, a packed column and a separation tube, 123 parts by weight of neopentyl glycol, 317 parts by weight of trimethylolpropane, 170 parts by weight of cyclohexanedimethanol, 114 parts by weight of DC-3074 (product of Dow Corning Co., Ltd.) and 474 parts by weight of hexahydrophthalic anhydride were charged, and the temperature was raised to 230 ℃ under a nitrogen atmosphere while removing condensed water. Then, when the acid value of the prepared resin reached 20mg KOH/g, the packed column was removed, and the reaction was continued. Then, when the acid value of the prepared resin reached 7mg KOH/g, the temperature was lowered to 130 ℃ and 480 parts by weight of butyl acetate was added to dilute to prepare silane-modified polyester polyol resin-1.

The silicone-modified polyester polyol resin-1 thus obtained had the following physical properties: a number average molecular weight of 928g/mol, a hydroxyl number of 250mg KOH/g, an acid number of 10mg KOH/g, a glass transition temperature of 10 ℃, a solids content of 70% by weight of the total weight and a Gardner viscosity of Y.

Synthesis example 2: preparation of Silicone-modified polyester polyol resins

Into a four-necked flask equipped with a thermometer, a stirring device, a condenser, a packed column and a separation tube, 306 parts by weight of neopentyl glycol, 87 parts by weight of trimethylolpropane, 141 parts by weight of cyclohexanedimethanol, 132 parts by weight of DC-3074 (product of Dow Corning Co., Ltd.) and 550 parts by weight of hexahydrophthalic anhydride were charged, and the temperature was raised to 230 ℃ under a nitrogen atmosphere while removing condensed water. Then, when the acid value of the prepared resin reached 20mgKOH/g, the packed column was removed, and the reaction was continued. Then, when the acid value of the prepared resin reached 7mgKOH/g, the temperature was lowered to 130 ℃ and 480 parts by weight of butyl acetate was added to dilute to prepare silane-modified polyester polyol resin-2.

The silicone-modified polyester polyol resin-2 thus obtained had the following physical properties: a number average molecular weight of 1,018g/mol, a hydroxyl number of 133.7mg KOH/g, an acid number of 35mg KOH/g, a glass transition temperature of-10 ℃, a solids content of 70% by weight in total and a Gardner viscosity of Y.

Synthesis example 3: preparation of acrylic polyol resin

To a four-necked flask equipped with a thermometer, a stirring device, a condenser and a heating device, 155 parts by weight of KOKOSOL #100, 15 parts by weight of ethyl ethoxypropionate and 148 parts by weight of glycidyl ester (HEXION co., CADURA E10P) purchased were charged, and the temperature was raised to 150 ℃. Then, if the temperature is stabilized to the isothermal temperature, the monomer mixture is added dropwise for 300 minutes, and the isothermal temperature is maintained for 120 minutes. In this case, a monomer mixture was prepared by mixing 208 parts by weight of styrene, 125 parts by weight of hydroxyethyl methacrylate, 54 parts by weight of acrylic acid, and 20 parts by weight of di-t-butyl peroxide.

Then, the reaction product was cooled to 80 ℃, and 100 parts by weight of butyl acetate and 100 parts by weight of KOKOSOL #100 were added to dilute to prepare an acrylic polyol resin.

The acrylic polyol resin thus obtained had the following physical properties: a solids content of 60% by weight, a Gardner viscosity of Z, a hydroxyl number of 150mg KOH/g, an acid number of 10mg KOH/g, a glass transition temperature of 40 ℃ and a number average molecular weight of 2,030 g/mol.

Synthesis example 4: preparation of polyester polyol resin

Into a four-necked flask equipped with a thermometer, a stirring device, a condenser, a packed column and a separation tube, 345 parts by weight of neopentyl glycol, 74 parts by weight of trimethylolpropane and 375 parts by weight of hexahydrophthalic anhydride were charged, and the temperature was raised to 230 ℃ under a nitrogen atmosphere while removing condensed water. Then, when the acid value of the prepared resin reached 25mg KOH/g, the packed column was removed, and the reaction was continued. Then, when the acid value of the prepared resin reached 7mg KOH/g, the temperature was lowered to 130 ℃ and 250 parts by weight of butyl acetate was added to dilute to prepare a polyester resin.

The polyester resin thus obtained had the following physical properties: a number average molecular weight of 350g/mol, a hydroxyl number of 255mg KOH/g, an acid number of 20mg KOH/g, a solids content of 75% by weight, and a Gardner viscosity of Z.

Examples 1 to 9 and comparative examples 1 to 3

Preparation of varnish compositions

The varnish compositions were prepared by stirring and mixing the components in the compositions described in tables 1 and 2 below at 1,500rpm for 20 minutes.

[ Table 1]

[ Table 2]

Hereinafter, manufacturers and product names of components used in comparative examples and examples are as follows.

-isocyanate resins: 1, 6-hexamethylene diisocyanate (1,6-HMDI) trimer, unreacted NCO content: 21.5 wt.%

-sagging control agent: acrylic polyol resin with hydroxyl and diurea groups, Setalux 81198SS-55 by Akzo Nobel Co.

-surface modifying agent: silicone based surfactant (BYK-331)

-a curing catalyst: KOKOSOL #100 comprising 10% by weight dibutyltin dilaurate (TL-1)

Light stabilizers: hindered amine based light stabilizers (Tinuvin 123 from BASF Co.)

-uv absorbers: tinuvin 384 of BASF co

Experimental example: measurement of physical Properties of coating film formed from coating composition

A topcoat paint (manufacturer: KCC, product name: WT3090) was applied to the sample and dried to form a topcoat film having a thickness of 15 μm. Then, each of the varnish compositions of examples and comparative examples was applied on the top-coat paint film, and cured at 100 ℃ for 25 minutes to form a varnish film having a thickness of 40 μm. For the samples, physical properties were measured by the following methods, and the results are shown in tables 3 and 4.

Specifically, by using a pistol type atomizer (nozzle diameter: 1.5mm, gas)Pressing: kept constant at about 4.5kgf/cm²) And moved in the horizontal direction at a speed of 40 cm/sec to 50 cm/sec while keeping the distance from the nozzle inlet to the sample constant at 30cm to form a varnish film.

(1) Hardness of

The hardness of the clear film was measured by the pencil hardness method. Specifically, the maximum hardness without damaging the clear paint film was measured by using each of 3B, 2B, HB, F, H, 2H and 3H pencils (3B, 2B, HB, F, H, 2H, 3H:

)。

(2) adhesion Property

The samples were heated and left to stand at room temperature for 24 hours, and the adhesion was evaluated by the checkerboard method (baduk board method).

Specifically, 100 squares having a length of 2mm and a width of 2mm were formed on the surface of the varnish film by a checkerboard method using a knife, and then the squares were separated using a tape to measure adhesiveness. In this case, the measured adhesion is expressed as follows: m-1 in the case where 100% of the 100 squares are all connected (very excellent), M-2 in the case where the remaining squares are 70% to less than 100% (excellent), M-3 in the case where the remaining squares are 50% to less than 70% (normal), M-4 in the case where the remaining squares are 30% to less than 50% (poor), and M-5 in the case where the remaining squares are less than 30% (very poor).

Further, the heat treatment was performed by heating at 150 ℃ for 20 minutes and standing at room temperature for 20 minutes, and the cycle was repeated three times in total.

(3) Water resistance

The specimen was immersed in a thermostatic water bath at 40 ℃ for 240 hours and left standing at room temperature for 1 hour, and subjected to a delamination test using the same method as the checkerboard method of item (2). Also, the same evaluation criteria apply.

(4) Acid resistance

On the surface of the coating film of the sample, 0.2ml of 0.1N sulfuric acid was dropped, and then treated in a pre-heating oven at 40 ℃ or more for 150 minutes. In this case, it was observed that etching, staining, or swelling occurred at the portion where sulfuric acid was dropped onto the sample, and the highest temperature at which no damage was caused to the sample was determined as the acid-resistant temperature.

(5) Scratch resistance

The 20 ° gloss of the sample was measured (initial gloss measurement), the surface of the sample was treated back and forth 10 times using a water-proof tester (product of Amtec Kistler co.), and then the 20 ° gloss was measured. Thereafter, using the initial gloss and the gloss after the surface treatment, the gloss retention ratio was calculated using the following mathematical formula 1.

[ mathematical formula 1]

Gloss retention ═ gloss after surface treatment/initial gloss × 100

(6) Solvent resistance

On the film coating of the sample, a cotton swab wetted with xylene was placed, the sample was scratched four times with a force of 2Kg per minute, and the time at which the surface below the film coating appeared was recorded.

[ Table 3]

Item

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Solid content in total weight (wt%)

52.6

50.4

56

51

61

52

Hardness of

F

HB

F

HB

Adhesion Property

M-1

M-2

M-1

Water resistance

M-1

M-2

Acid resistance

45℃

41℃

44℃

43℃

40℃

Scratch resistance (gloss retention)

65％

60％

64％

63％

61％

60％

Solvent resistance

10 minutes

9 minutes

10 minutes

8 minutes

Initial gloss

89％

84％

88％

89％

84％

85％

[ Table 4]

Item

Example 7

Example 8

Example 9

Comparative example 1

Comparative example 2

Comparative example 3

Solid content in total weight (wt%)

54

45

38

42.7

39

Hardness of

HB

B

2B

B

3B

Adhesion Property

M-1

M-2

M-5

M-3

Water resistance

M-2

M-3

M-2

M-3

Acid resistance

41℃

38℃

36℃

37℃

Scratch resistance (gloss retention)

59％

57％

52％

54％

53％

Solvent resistance

7 minutes

6 minutes

5 minutes

Initial gloss

84％

83％

82％

81％

As shown in tables 3 and 4, the coating films formed from the varnish compositions of examples 1 to 9 exhibited excellent mechanical properties including hardness, adhesion, water resistance, acid resistance, scratch resistance, solvent resistance and initial gloss.

In contrast, the coating film formed from the composition of comparative example 1 (not containing the silicone-modified polyester polyol resin) and the coating film formed from the composition of comparative example 3 (not containing the polyester resin) exhibited insufficient hardness and solvent resistance. In addition, the coating film formed from the varnish composition of comparative example 2 (containing no acrylic polyol resin) exhibited very poor adhesion and insufficient solvent resistance.

As described above, the varnish composition according to the present invention can be cured at a low temperature of 120 ℃ or less than 120 ℃, and can save costs consumed during a coating process, and is economical. Further, the vehicle body and the material member joined thereto can be integrally painted, and defects of different colors of the member and the vehicle body after painting can be prevented. Further, a coating film formed from the varnish composition has excellent physical properties such as hardness, adhesion, water resistance, acid resistance, scratch resistance and solvent resistance, and is useful for coating a vehicle body.

Claims

1. A varnish composition comprising a silicone-modified polyester polyol resin, an acrylic polyol resin, a polyester resin, and an isocyanate resin.

2. The varnish composition of claim 1 wherein the silicone-modified polyester polyol resin has a hydroxyl number of 150 to 350mg KOH/g, an acid number greater than 0 and less than 30mg KOH/g, a number average molecular weight of 100 to 10,000g/mol, and a glass transition temperature of-50 to 30 ℃.

3. The varnish composition of claim 1 wherein the acrylic polyol resin has a hydroxyl number of 80 to 200mg KOH/g, an acid number greater than 0 and 30mg KOH/g or less, a number average molecular weight of 1,000 to 10,000g/mol, and a glass transition temperature greater than 0 and 70 ℃ or less.

4. The varnish composition of claim 1 wherein the polyester resin has a number average molecular weight of 100 to 700g/mol, a hydroxyl value of 100 to 400mgKOH/g, and an acid value of 1 to 30 mgKOH/g.

5. The varnish composition of claim 1 wherein the varnish composition comprises 1 to 30 parts by weight of the silicone-modified polyester polyol resin, 1 to 30 parts by weight of the acrylic polyol resin, 5 to 40 parts by weight of the polyester resin, and 10 to 40 parts by weight of the isocyanate resin.