Water-soluble paint composition

Abstract

The present invention provides a water-soluble paint composition which has excellent hardness and adhesion and can be cured at a low temperature of less than 100°C. The water-soluble paint composition comprises a main agent including: an acrylic dispersion resin having a unit derived from polyalkylene glycol mono(meth)acrylate; a polyester resin; an acrylic emulsion resin; and a water-soluble polyurethane resin, and a curing agent including an isocyanate-based resin, wherein the content of the unit derived from polyalkylene glycol mono(meth)acrylate may be 5-13 wt % on the basis of the total weight of monomers contained in the acrylic dispersion resin.

Description

Water-soluble paint composition

[0001] The present invention relates to a water-soluble paint composition that can secure excellent hardness and adhesion and can be cured at a low temperature of less than 100°C.

[0002] After the car body is completed, it is painted to prevent surface corrosion from the external environment, improve soundproofing, and enhance its appearance.

[0003] The above-mentioned painting process includes multiple painting steps. Specifically, the painting process includes a step of painting an electrodeposition paint on a vehicle body that has undergone a pretreatment process and then curing it, a step of painting an intermediate paint to improve adhesion and chipping resistance and then curing it, a step of painting a top coat (base paint) on the intermediately painted vehicle body surface to improve the appearance of the vehicle body and then curing it, and a step of painting a clear coat and then curing it to protect the color and the paint film from the outside.

[0004] Meanwhile, research into developing eco-friendly and economical paints has recently emerged. Specifically, Korean Patent Publication No. 2011-0147566 discloses a "water-soluble automotive intermediate paint composition" comprising polyester, acrylic, polyurethane dispersion resin, and a melamine curing agent, thereby improving properties such as film hardness and popping resistance. Korean Patent Registration No. 10-0773135 discloses a water-soluble automotive intermediate paint composition comprising polyester, polyurethane, and alkyd resin, thereby improving appearance and mechanical properties.

[0005] However, since most paint compositions carry out the curing process at high temperatures of 130℃ or higher, there were limitations in suppressing the generation of volatile organic compounds caused during the painting process.

[0006] Accordingly, there is a need for research and development of a water-soluble paint composition that can perform a complete curing process at a temperature below 100°C while ensuring excellent mechanical properties (hardness) and adhesion, and at the same time suppressing the generation of volatile organic compounds.

[0007] Prior art literature

[0008] Republic of Korea Patent Publication No. 2011-0147566

[0009] Republic of Korea Patent No. 10-0773135

[0010] The present invention is intended to solve the above-described problems, and provides a water-soluble paint composition that can be completely cured at a temperature of less than 100°C by including an acrylic dispersion resin containing a unit derived from a polyalkylene glycol mono(meth)acrylate monomer as a main component in a specific content range.

[0011] According to one embodiment, the present invention

[0012] A subject matter comprising an acrylic dispersion resin comprising a unit derived from a polyalkylene glycol mono(meth)acrylate monomer; a polyester resin; an acrylic emulsion resin; and a water-soluble polyurethane resin; and

[0013] Contains a curing agent containing an isocyanate resin,

[0014] A water-soluble paint composition is provided in which the unit content derived from the polyalkylene glycol mono(meth)acrylate monomer is 5 wt% to 13 wt% based on the total weight of monomers contained in the acrylic dispersion resin.

[0015] The above acrylic dispersion resin may have a glass transition temperature (Tg) of 20°C to 60°C, a hydroxyl value (OHv) of 80 mg KOH / g to 150 mg KOH / g, an acid value (Av) of 9 mg KOH / g to 25 mg KOH / g, a number average molecular weight of 5,000 g / mol to 10,000 g / mol, and a weight average molecular weight of 10,000 g / mol to 20,000 g / mol.

[0016] The above acrylic dispersion resin may additionally include at least one of a unit derived from an epoxy-containing ester monomer, a unit derived from an ethylenically unsaturated monomer, and a unit derived from a hydroxyl group-containing acrylic monomer.

[0017] The above water-soluble polyurethane resin may have an acid value of 10 mg KOH / g to 30 mg KOH / g.

[0018] The above water-soluble paint composition may contain 15 to 30 parts by weight of acrylic dispersion resin, 2 to 10 parts by weight of polyester resin, 1 to 5 parts by weight of acrylic emulsion resin, and 12 to 20 parts by weight of water-soluble polyurethane resin, based on 100 parts by weight of the main component.

[0019] Additionally, the water-soluble paint composition may have a complete curing time of 20 minutes or less at 100°C or less.

[0020] The water-soluble paint composition of the present invention comprises an acrylic dispersion resin containing 5 to 13 wt% of a unit derived from a polyalkylene glycol mono(meth)acrylate monomer as a main component and a water-soluble polyurethane resin having an acid value of 10 to 30 mg KOH / g, thereby being able to form a coating film that can be cured in a short time at a low temperature of less than 100°C, thereby ensuring excellent hardness and adhesion. The water-soluble paint composition of the present invention can be applied in various ways as an intermediate coating for transportation means such as automobiles.

[0021] Hereinafter, the present invention will be described in more detail.

[0022] Meanwhile, in this specification, “includes” is an open description having an equivalent meaning to expressions such as “comprises,” “contains,” “has,” or “characterizes,” and does not exclude elements, materials, or processes that are not additionally listed.

[0023] In addition, units used in this specification without special mention are based on weight, and for example, units of % or ratio mean weight% (wt%) or weight ratio.

[0024] In this specification, "molecular weight" means weight average molecular weight (Mw) unless otherwise defined, and the weight average molecular weight (Mw) of the polymer of the present invention can be measured using gel permeation chromatography (GPC). For example, after preparing a sample of a certain concentration, the GPC measuring device is stabilized, and once the device is stabilized, a standard sample and a sample are injected into the device to obtain a chromatogram, and then the molecular weight can be calculated according to the analysis method.

[0025] In this specification, functional groups such as “acid value” and “hydroxyl value” are measured by conventional methods known in the art, and can be measured by, for example, a titration method.

[0026]

[0027] The water-soluble paint composition according to the present invention

[0028] A subject matter comprising an acrylic dispersion resin comprising a unit derived from a polyalkylene glycol mono(meth)acrylate monomer; a polyester resin; an acrylic emulsion resin; and a water-soluble polyurethane resin; and

[0029] Contains a curing agent containing an isocyanate resin,

[0030] The content of the unit derived from the above polyalkylene glycol mono(meth)acrylate monomer may be 5 wt% to 13 wt% based on the total weight of the monomer contained in the acrylic dispersion resin.

[0031]

[0032] A. Topic

[0033] 1) Acrylic dispersion resin

[0034] The above acrylic dispersion resin is included as a main component of a water-soluble paint composition, thereby improving the storage properties and chemical resistance of the water-soluble paint composition, and enabling rapid drying and curing reactions of the water-soluble paint composition even at low temperatures of 100°C or lower.

[0035] The above acrylic dispersion resin may include units derived from polyalkylene glycol mono(meth)acrylate monomers.

[0036] The content of the unit derived from the polyalkylene glycol mono(meth)acrylate monomer may be 5 wt% or more, 6 wt% or more, 7 wt% or more, or 8 wt% or more, based on the total weight of the monomer contained in the acrylic dispersion resin. In addition, the content of the unit derived from the polyalkylene glycol mono(meth)acrylate monomer may be 13 wt% or less, 12 wt% or less, 11 wt% or less, or 10 wt% or less, based on the total weight of the monomer contained in the acrylic dispersion resin. The above numerical ranges may be combined with each other without limitation. Specifically, the content of the unit derived from the polyalkylene glycol mono(meth)acrylate monomer may be 5 wt% to 13 wt%, or 5 wt% to 10 wt%, based on the total weight of the monomer contained in the acrylic dispersion resin.

[0037] When the unit content derived from the polyalkylene glycol mono(meth)acrylate monomer is less than 5 wt%, poor appearance of the coating film and reduced impact resistance may occur, and further, due to insufficient hydrophilic components, the content of the hardener may remain excessively, making it impossible to cure the coating composition at temperatures below 100°C. In addition, when the unit content derived from the polyalkylene glycol mono(meth)acrylate monomer exceeds 13 wt%, poor appearance of the coating film and deterioration of water resistance may occur, and further, due to excessive increase in the hydrophilic components, unreacted groups may exist, making it impossible to cure the coating composition at temperatures below 100°C.

[0038] Meanwhile, the acrylic dispersion resin may additionally include a unit derived from an epoxy-containing ester monomer.

[0039] The epoxy group contained in the molecule of the above epoxy-containing ester monomer can react with an ethylenically unsaturated monomer containing a carboxyl group (-C(O)-OH) described below to form a hydroxy ester functional group. The hydroxy ester functional group thus formed can react with a curing agent described below to induce a curing reaction, thereby ensuring excellent film curing of the paint composition. Examples of the above epoxy-containing ester monomer include neodecanoic acid glycidyl ester (Neodecanoic Acid Glycidyl Ester, Hexion, Cardura E10P).

[0040] Meanwhile, the content of the unit derived from the epoxy-containing ester monomer may be 1 wt% or more, 2 wt% or more, 3 wt% or more, or 5 wt% or more, and may also be 50 wt% or less, 45 wt% or less, 40 wt% or less, 45 wt% or less, or 30 wt% or less, based on the total weight of the monomers contained in the acrylic dispersion resin. The above numerical ranges may be combined with each other without limitation. Specifically, the content of the unit derived from the epoxy-containing ester monomer may be 1 wt% to 50 wt%, 1 wt% to 40 wt%, or 1 wt% to 30 wt% based on the total weight of the monomers contained in the acrylic dispersion resin.

[0041] When the content of the unit derived from the epoxy-containing ester monomer is less than 1 wt%, the initial raw material content is insufficient during the synthesis of the acrylic dispersion resin, so not only cannot secure excellent coating curing degree, but also the solvent must be increased for the synthesis reaction, which increases the manufacturing cost and causes the generation of volatile organic substances. In addition, when the content of the unit derived from the epoxy-containing ester monomer exceeds 50 wt%, there is a problem that the curing speed slows down as the hydroxyl group, which is a functional group, excessively increases in the acrylic dispersion resin.

[0042] In addition, the acrylic dispersion resin may additionally include at least one of (i) a unit derived from an ethylenically unsaturated monomer and (ii) a unit derived from a hydroxyl group-containing acrylic monomer.

[0043] The above (i) ethylenically unsaturated monomer may include an ethylenically unsaturated monomer containing a carboxyl group (-C(O)-OH). The ethylenically unsaturated monomer containing a carboxyl group may be at least one of acrylic acid and methacrylic acid.

[0044] In addition, the above (i) ethylenically unsaturated monomer may additionally include an ethylenically unsaturated monomer that does not contain a carboxyl group.

[0045] The ethylenically unsaturated monomer not containing a carboxyl group may be at least one selected from the group consisting of styrene, methyl acrylate, ethyl acrylate, propyl acrylate, isobutylacrylate, tert-butylacrylate, 2-ethylhexylacrylate, normal butylacrylate, methyl(meth)acrylate, propyl(meth)acrylate, normal butyl(meth)acrylate, isobutyl(meth)acrylate, tert-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, or lauryl(meth)acrylate, and preferably at least one of styrene, normal butylacrylate, and methyl(meth)acrylate.

[0046] The content of the unit derived from the ethylenically unsaturated monomer may be 30 wt% or more, 35 wt% or more, 40 wt% or more, or 45 wt% or more, based on the total weight of the monomers contained in the acrylic dispersion resin. In addition, the content of the unit derived from the ethylenically unsaturated monomer may be 70 wt% or less, 65 wt% or less, or 60 wt% or less, based on the total weight of the monomers contained in the acrylic dispersion resin. The above numerical ranges may be combined with each other without limitation. Specifically, the content of the unit derived from the ethylenically unsaturated monomer may be 30 wt% to 70 wt%, or 35 wt% to 65 wt%, based on the total weight of the monomers contained in the acrylic dispersion resin.

[0047] When the content of the unit derived from the above ethylenically unsaturated monomer satisfies the above range, the effect of improving the adhesion and water resistance of the coating film can be obtained, and excellent coating film appearance characteristics can be secured.

[0048] In addition, (ii) the hydroxyl group-containing acrylic monomer may include, but is not limited to, 2-hydroxymethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxymethyl(meth)acrylate, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, 2-hydroxybutyl(meth)acrylate, 4-hydroxybutyl(meth)acrylate, 6-hydroxyhexyl(meth)acrylate, 2,3-dihydroxypropyl acrylate, or 2,3-dihydroxypropyl(meth)acrylate. Specifically, the hydroxyl group-containing acrylic monomer may be 2-hydroxyethyl acrylate, 2-hydroxymethyl (meth)acrylate or 2-hydroxyethyl (meth)acrylate.

[0049] The content of the unit derived from the hydroxyl group-containing acrylic monomer may be 5 wt% or more, 6 wt% or more, 7 wt% or more, 8 wt% or more, 9 wt% or more, or 10 wt% or more, based on the total weight of the monomers contained in the acrylic dispersion resin. In addition, the content of the unit derived from the hydroxyl group-containing acrylic monomer may be 30 wt% or less, 28 wt% or less, 27 wt% or less, 26 wt% or less, or 25 wt% or less, based on the total weight of the monomers contained in the acrylic dispersion resin. The above numerical ranges may be combined with each other without limitation. Specifically, the content of the unit derived from the hydroxyl group-containing acrylic monomer may be 5 wt% to 30 wt%, or 10 wt% to 25 wt%, based on the total weight of the monomers contained in the acrylic dispersion resin.

[0050] When the unit content derived from the above hydroxyl group-containing acrylic monomer satisfies the above range, excellent coating film adhesion and solvent resistance can be achieved. On the other hand, when the unit content derived from the above hydroxyl group-containing acrylic monomer is less than 5 wt%, the curing speed is reduced, so that curing may not occur well at temperatures below 100°C, and when it exceeds 30 wt%, water resistance may be affected.

[0051] Meanwhile, the acrylic dispersion resin of the present invention can be obtained by mixing a resin obtained by solution polymerizing an epoxy-containing ester monomer, an ethylenically unsaturated monomer, and an acrylic monomer containing a hydroxyl group together with a polyalkylene glycol mono(meth)acrylate monomer in the presence of a radical polymerization initiator, with a neutralizing agent and a curing accelerator.

[0052] Specifically, the acrylic dispersion resin can be manufactured by the steps of: first mixing a reaction solvent and an epoxy-containing ester monomer, for example, Cardura E10P, and heating the reactant to 140 to 150°C; adding a primary polymerization initiator to the reactant, and further adding dropwise and stirring an ethylenically unsaturated monomer and / or a hydroxyl group-containing acrylic monomer and a polyalkylene glycol mono(meth)acrylate monomer in the presence of the primary polymerization initiator; further adding dropwise a secondary polymerization initiator to the manufactured reactant and cooling to 50°C; adding dropwise a neutralizing agent and distilled water to the manufactured reactant; adding a curing accelerator to the manufactured reactant and stirring; and cooling the manufactured reactant to 40°C to terminate the reaction and obtain an acrylic dispersion resin without an additional filtration process.

[0053] At this time, the mixing ratio of the polyalkylene glycol mono(meth)acrylate monomer, the epoxy-containing ester monomer, the ethylenically unsaturated monomer, and the hydroxyl group-containing acrylic monomer can be appropriately controlled so that units derived from each monomer in the acrylic dispersion resin of the present invention can be included in a limited content range.

[0054] In addition, as the reaction solvent, a solvent compatible with water (compatible solvent) such as an alcohol-based solvent such as Butyl Cellosolve, Butyl Carbitol, DOWANOL DPnB (DOW), or an ester-based solvent such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, ethyl ethoxypropionate, etc. can be used.

[0055] The above primary and secondary polymerization initiators may each independently be at least one selected from the group consisting of potassium persulfate, peroxide, tert-butyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, tert-butyl perfivalate, tert-amyl perbenzoate, tert-amyl peroxyacetate, di-tert-amyl peroxide, tert-amyl peroxyneodecanoate, tert-butyl peroxyneodecanoate, tert-amyl-(2-ethylesyl)monoperoxycarbonate, azobisisobutylnitrile, and 2.2-azobis methylbutyronitrile, and the above primary and secondary polymerization initiators may be the same or different from each other. Preferably, the primary and secondary polymerization initiators may be the same.

[0056] In addition, the total content of the primary and secondary polymerization initiators may be used in an amount of 0.1 part by weight or more, 0.5 part by weight or more, or 1 part by weight or more, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin. In addition, the total content of the primary and secondary polymerization initiators may be used in an amount of 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin. Specifically, the total content of the primary and secondary polymerization initiators may be used in an amount of 0.1 to 5 parts by weight, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin.

[0057] When the total content of the primary and secondary polymerization initiators satisfies the above range, excellent film hardness and adhesion can be obtained.

[0058] In addition, the curing accelerator is a component that acts as a catalyst to promote curing and increase crosslinking density, and a representative example thereof may include at least one of dibutyltin dilaurate and dibutyltin diacetate.

[0059] The above curing accelerator may be used in an amount of 0.1 to 5 parts by weight, or 0.1 to 0.5 parts by weight, based on 100 parts by weight of the total acrylic dispersion resin.

[0060] When the content of the curing accelerator satisfies the above range, excellent coating film water resistance and adhesion can be obtained. When the content of the curing accelerator is less than 0.1 part by weight, the curing speed is slow, and curing does not occur at temperatures below 100°C, making it difficult to obtain a cured coating film. In addition, when the content of the curing accelerator exceeds 0.5 part by weight, curing occurs too quickly before a uniform coating film is formed, which may cause problems with the appearance of the coating film.

[0061] In addition, the neutralizing agent is a component that combines with an ethylenically unsaturated monomer containing a carboxyl group (-C(O)-OH) to enable the acrylic dispersion resin to be dispersed in water, and may include a tertiary amine such as triethyldiamine, triethanolamine, dimethylethanolamine, and dimethylcyclohexylamine.

[0062] The neutralizing agent may be used in an amount of 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin. In addition, the neutralizing agent may be used in an amount of 10 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, or 6 parts by weight, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin. Specifically, the neutralizing agent may be used in an amount of 1 to 10 parts by weight, or 2 to 6 parts by weight, based on 100 parts by weight of the total monomer contained in the acrylic dispersion resin. When the neutralizing agent content satisfies the above range, an excellent water dispersing effect can be obtained. On the other hand, when the neutralizing agent is less than 1 part by weight, the water dispersing effect is poor, and acrylic dispersion resin synthesis may not be achieved. When it exceeds 10 parts by weight, the viscosity of the acrylic dispersion resin increases, which may cause a problem of deterioration in subsequent workability.

[0063] Meanwhile, the glass transition temperature (Tg) of the acrylic dispersion resin of the present invention may be 20°C or higher, 25°C or higher, 30°C or higher, 34°C or higher, or 35°C or higher. In addition, the glass transition temperature (Tg) of the acrylic dispersion resin of the present invention may be 60°C or lower, 58°C or lower, 56°C or lower, or 55°C or lower. Specifically, the glass transition temperature (Tg) of the acrylic dispersion resin may be 20°C to 60°C, or 40°C to 60°C. The glass transition temperature (T) of the acrylic dispersion resin g ) satisfies the above range, the drying property of the paint composition can be improved, and excessive use of solvent due to quick drying can be suppressed.

[0064] The hydroxyl value (OHv) of the above acrylic dispersion resin may be 80 mg KOH / g or more, 82 mg KOH / g or more, 85 mg KOH / g or more, 87 mg KOH / g or more, 90 mg KOH / g or more, 92 mg KOH / g or more, 95 mg KOH / g or more, 97 mg KOH / g or more, or 100 mg KOH / g or more. In addition, the hydroxyl value (OHv) of the above acrylic dispersion resin may be 150 mg KOH / g or less, 148 mg KOH / g or less, 146 mg KOH / g or less, 142 mg KOH / g or less, 140 mg KOH / g or less, or 135 mg KOH / g or less. Specifically, the hydroxyl value (OHv) of the acrylic dispersion resin may be 80 mg KOH / g to 150 mg KOH / g, or 100 mg KOH / g to 150 mg KOH / g. When the hydroxyl value of the acrylic dispersion resin satisfies the above range, synthetic stability can be secured and a decrease in water resistance can be prevented.

[0065] In addition, the acid value (Av) of the acrylic dispersion resin may be 9 mg KOH / g or more or 10 mg KOH / g or more. In addition, the acid value (Av) of the acrylic dispersion resin may be 25 mg KOH / g or less, 24 mg KOH / g or less, 23 mg KOH / g or less or 20 mg KOH / g or less. Specifically, the acid value (Av) of the acrylic dispersion resin may be 9 mg KOH / g to 25 mg KOH / g or 10 mg KOH / g to 25 mg KOH / g. When the acid value of the acrylic dispersion resin satisfies the above range, storage stability can be secured.

[0066] In addition, the number average molecular weight of the acrylic dispersion resin may be 5,000 g / mol or more, 5,500 g / mol or more, 6,000 g / mol or more, 6,500 g / mol or more, 7,000 g / mol or more, 7,500 g / mol or more, 7,700 g / mol or more, or 8,000 g / mol or more. In addition, the number average molecular weight of the acrylic dispersion resin may be 10,000 g / mol or less, 9,800 g / mol or less, or 9,600 g / mol or less. Specifically, the number average molecular weight of the acrylic dispersion resin may be 5,500 g / mol to 10,000 g / mol, and may be 7,000 g / mol to 10,000 g / mol.

[0067] In addition, the weight average molecular weight of the acrylic dispersion resin may be 10,000 g / mol or more, 15,000 g / mol or more, 17,000 g / mol or more, or 18,000 g / mol or more. In addition, the weight average molecular weight of the acrylic dispersion resin may be 20,000 g / mol or less, 19,900 g / mol or less, or 19,800 g / mol or less. Specifically, the weight average molecular weight of the acrylic dispersion resin may be 10,000 g / mol to 20,000 g / mol, or 15,000 g / mol to 20,000 g / mol.

[0068] In addition, the polydispersity index (PDI, Mw / Mn) of the acrylic dispersion resin may be 2.0 to 5.0 or 2.0 to 4.0. Specifically, when the number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (PDI) of the polyester resin satisfy the above ranges, mechanical properties can be secured and deterioration of appearance can be prevented.

[0069] In addition, the viscosity of the acrylic dispersion resin measured at 25°C may be 1,000 cps or more, 1,200 cps or more, 1,300 cps or more, 1,400 cps or more, or 1,500 cps or more. The viscosity of the acrylic dispersion resin measured at 25°C may be 3,000 cps or less, 2,500 cps or less, 2,000 cps or less, 1,900 cps or less, 1,700 cps or less, or 1,650 cps or less. Specifically, the viscosity of the acrylic dispersion resin measured at 25°C may be 1,000 cps to 3,000 cps, or 1,000 cps to 2,000 cps. The viscosity may be measured using a Brookfield viscometer (Brookfield viscometer B type). When the viscosity of the first acrylic resin emulsion is 1,000 cps or more, storage stability can be ensured, and when it is 3,000 cps or less, application properties are excellent, making work easy.

[0070] Furthermore, the acrylic dispersion resin may be included in an amount of 15 parts by weight or more, 16 parts by weight or more, 17 parts by weight or more, 18 parts by weight or more, 19 parts by weight or more, or 20 parts by weight or more, based on 100 parts by weight of the main component. In addition, the acrylic dispersion resin may be included in an amount of 30 parts by weight or less, 29 parts by weight or less, or 28 parts by weight or less, based on 100 parts by weight of the main component. The above numerical ranges may be combined with each other without limitation. Specifically, the acrylic dispersion resin may be included in an amount of 15 to 30 parts by weight, or 20 to 30 parts by weight, based on 100 parts by weight of the main component. When the content of the acrylic dispersion resin satisfies the above range, not only can a coating film be formed that can be cured in a short time at a temperature of 100°C or less be formed, but also high gloss of the paint can be implemented, and impact resistance and chipping resistance are improved. Specifically, when the content of the acrylic dispersion resin is 15 parts by weight or more, the coating film curing ability is improved, thereby ensuring excellent paint stability, hardness, and mechanical properties. In addition, when the content of the acrylic dispersion resin is 30 parts by weight or less, the coating film curing ability can be improved at low temperatures.

[0071]

[0072] 2) Polyester resin

[0073] The above polyester resin is a synthetic resin obtained by a condensation reaction of glycol and acid in the presence of an organic or inorganic catalyst, and can form a dense film structure by forming a branching structure by the acid component.

[0074] Representative examples of the above glycols include ethylene glycol, neopentyl glycol, propylene glycol, 1.4-butylene glycol, 1,6-hexanediol, methylpropanediol, and cyclohexanedimethanol, and these may be used alone or in a mixture of two or more.

[0075] In addition, the acid component may be adipic acid, isophthalic acid, isophthalic acid, azelaic acid, terephthalic acid, phthalic anhydride, hexahydrophthalic anhydride, or tetrahydrophthalic anhydride, used alone or in combination of two or more thereof.

[0076] The glass transition temperature (Tg) of the polyester resin may be -10°C or higher, -8°C or higher, or -7°C or higher. In addition, the glass transition temperature (Tg) of the polyester resin may be 10°C or lower, 8°C or lower, 6°C or lower, or 5°C or lower. When the glass transition temperature (Tg) of the polyester resin satisfies the above range, the drying property of the paint composition may be improved, and excessive use of solvent due to quick drying property may be suppressed.

[0077] Additionally, the acid value (Av) of the polyester resin may be 20 mg KOH / g to 40 mg KOH / g, or may be 20 mg KOH / g to 30 mg KOH / g.

[0078] When the acid value of the polyester resin satisfies the above range, crosslinking density and curing reactivity effects can be secured, so that a coating film having excellent mechanical properties can be formed.

[0079] Additionally, the hydroxyl value (OHv) of the polyester resin may be 50 mg KOH / g or more, 60 mg or more, or 70 mg KOH / g or more. Additionally, the hydroxyl value (OHv) of the polyester resin may be 100 mg KOH / g or less, 95 mg KOH / g or less, or 90 mg KOH / g or less.

[0080] When the hydroxyl value of the polyester resin satisfies the above range, there is an effect of improving the physical properties of the manufactured coating film, such as adhesion and solvent resistance, by improving low-temperature curing and crosslinking density with the curing agent.

[0081] Additionally, the number average molecular weight (Mn) of the polyester resin may be 1,000 g / mol or more or 1,500 g / mol or more. Additionally, the number average molecular weight (Mn) of the polyester resin may be 2,000 g / mol or less or 1,900 g / mol or less.

[0082] In addition, the weight average molecular weight (Mw) of the polyester resin may be 2,000 g / mol or more, 2,200 g / mol or more, 2,400 g / mol or more, 2,600 g / mol or more, 2,800 g / mol or more, or 3,000 g / mol or more. In addition, the weight average molecular weight (Mw) of the polyester resin may be 4,000 g / mol or less, or 3,800 g / mol or less.

[0083] Additionally, the polydispersity index (PDI, Mw / Mn) of the polyester resin may be 2.0 to 5.0, and specifically 2.0 to 4.0.

[0084] When the above number average molecular weight (Mn), weight average molecular weight and polydispersity index all satisfy the above ranges, excellent film stability and adhesion can be secured, and the smoothness is excellent, thereby improving the appearance characteristics of the film.

[0085] The above polyester resin may be a polyester resin having a solid content of 60 wt% to 90 wt% based on the total weight of the resin.

[0086] Furthermore, the polyester resin may be included in an amount of 2 parts by weight or more, 3 parts by weight or more, or 4 parts by weight or more, based on 100 parts by weight of the main body. The polyester resin may be included in an amount of 10 parts by weight or less, 9 parts by weight or less, or 8 parts by weight or less, based on 100 parts by weight of the main body. The above numerical ranges may be combined without limitation. Specifically, the polyester resin may be included in an amount of 2 to 10 parts by weight, or 2 to 8 parts by weight, based on 100 parts by weight of the main body. When the content of the polyester resin satisfies the above range, not only can a solid coating film be formed, but also high gloss of the coating material can be realized, and impact resistance and chipping resistance are improved. Specifically, when the content of the polyester resin is 2 parts by weight or more, the coating film orientation ability is improved, so that excellent coating stability and mechanical properties (hardness, etc.) can be secured. In addition, when the content of the polyester resin is 10 parts by weight or less, the content of the acrylic resin can be relatively secured, so that the curing property of the coating film can be improved at low temperatures.

[0087]

[0088] 3) Acrylic emulsion resin

[0089] The above acrylic emulsion resin is a component that affects the overall physical properties of the coating film, such as the appearance of the coating film, interlayer penetration prevention, leveling, wettability, adhesion, and water resistance, and may be included to provide dispersion stability and storage stability of the pigment.

[0090] The above acrylic emulsion resin may be copolymerized from a mixture of two or more acrylic monomers, and specifically, a lipophilic acrylic emulsion resin copolymerized with butylacrylate monomer and methylmethacrylate monomer as the basic structure may be used.

[0091] The glass transition temperature (Tg) of the above acrylic emulsion resin may be -10°C or higher, -8°C or higher, or -7°C or higher. In addition, the glass transition temperature (Tg) of the acrylic emulsion resin may be 10°C or lower, 8°C or lower, 6°C or lower, or 5°C or lower. When the glass transition temperature (Tg) of the above acrylic emulsion resin satisfies the above range, the drying property of the paint composition may be improved, and excessive use of solvent due to quick drying property may be suppressed.

[0092] In addition, the acrylic emulsion resin may have a hydroxyl value (OHV) of 1 mg KOH / g or more, 2 mg KOH / g or more, 3 mg KOH / g or more, or 4 mg KOH / g or more. In addition, the acrylic emulsion resin may have a hydroxyl value (OHV) of 20 mg KOH / g or less, 18 mg KOH / g or less, 16 mg KOH / g or less, 14 mg KOH / g or less, 12 mg KOH / g or less, or 10 mg KOH / g or less.

[0093] When the hydroxyl value of the above acrylic emulsion resin satisfies the above range, the orange peel improvement effect of the paint can be obtained.

[0094] Additionally, the acrylic emulsion resin may have an acid value (Av) of 1 mg KOH / g to 30 mg KOH / g, or 5 mg KOH / g to 20 mg KOH / g.

[0095] When the acid value (Av) of the above acrylic emulsion resin satisfies the above range, the leveling (long wave) of the paint can be improved.

[0096] In addition, the number average molecular weight (Mn) of the acrylic emulsion resin may be 10,000 g / mol or more, 11,000 g / mol or more, or 13,000 g / mol or more. In addition, the number average molecular weight (Mn) of the acrylic emulsion resin may be 50,000 g / mol or less, 48,000 g / mol or less, 46,000 g / mol or less, 44,000 g / mol or less, 42,000 g / mol or less, or 40,000 g / mol or less.

[0097] In addition, the weight average molecular weight (Mw) of the acrylic emulsion resin may be 100,000 g / mol or more, 110,000 g / mol or more, or 120,000 g / mol or more. In addition, the weight average molecular weight (Mw) of the acrylic emulsion resin may be 200,000 g / mol or less, 190,000 g / mol or less, 180,000 g / mol or less, 170,000 g / mol or less, 160,000 g / mol or less, or 150,000 g / mol or less.

[0098] Additionally, the polydispersity index (PDI, Mw / Mn) of the acrylic emulsion resin may be 2.0 to 5.0, and specifically 2.0 to 4.0.

[0099] When the above number average molecular weight (Mn), weight average molecular weight and polydispersity index all satisfy the above ranges, high gloss can be achieved and there is an effect of improving high appearance and durability.

[0100] The above acrylic emulsion resin preferably has a solid content of 35 wt% to 45 wt% based on the total weight of the resin.

[0101] Furthermore, the acrylic emulsion resin may be included in an amount of 1 part by weight or more or 2 parts by weight or more relative to 100 parts by weight of the main component. In addition, the acrylic emulsion resin may be included in an amount of 5 parts by weight or less or 4 parts by weight or less relative to 100 parts by weight of the main component. The above numerical ranges may be combined with each other without limitation. Specifically, the acrylic emulsion resin may be included in an amount of 1 to 5 parts by weight or 1 to 4 parts by weight relative to 100 parts by weight of the main component.

[0102] When the content of the above acrylic emulsion resin is 1 part by weight or more, excellent film forming ability, drying properties, and mechanical properties can be secured, and when it is 5 parts by weight or less, paint wettability and leveling properties are improved, forming an excellent film appearance, and cold chipping resistance and impact resistance can be improved.

[0103]

[0104] 4) Water-soluble polyurethane resin

[0105] The above water-soluble polyurethane resin can be used to improve the suitable wettability, chemical resistance, adhesion, water resistance, impact resistance, and chipping resistance of the coating film.

[0106] The above water-soluble polyurethane resin may be a resin manufactured by a polymerization reaction of dimethylolpropionic acid, polycarbonate polyol, diisocyanate, and amine under an acetone process.

[0107] The glass transition temperature (Tg) of the water-soluble polyurethane resin may be -20°C or higher, -15°C or higher, or -10°C or higher. In addition, the glass transition temperature (Tg) of the water-soluble polyurethane resin may be 10°C or lower, 8°C or lower, 6°C or lower, or 5°C or lower. When the glass transition temperature (Tg) of the water-soluble polyurethane resin satisfies the above range, the drying property of the paint composition may be improved, and excessive use of solvent due to quick drying property may be suppressed.

[0108] In addition, the water-soluble polyurethane resin may have a hydroxyl value (OHv) of 50 mg KOH / g or more, 52 mg KOH / g or more, 54 mg KOH / g or more, 56 mg KOH / g or more, 58 mg KOH / g or more, or 60 mg KOH / g or more. In addition, the water-soluble polyurethane resin may have a hydroxyl value (OHv) of 100 mg KOH / g or less, 98 mg KOH / g or less, 96 mg KOH / g or less, 94 mg KOH / g or less, 92 mg KOH / g or less, or 90 mg KOH / g or less.

[0109] When the hydroxyl value of the above water-soluble polyurethane resin satisfies the above range, excellent hardness and stability can be secured.

[0110] In addition, the water-soluble polyurethane resin may have an acid value of 10 mg KOH / g or more, 11 mg KOH / g or more, or 12 mg KOH / g or more. In addition, the water-soluble polyurethane resin may have an acid value of 30 mg KOH / g or less, 27 mg KOH / g or less, or 25 mg KOH / g. The above numerical ranges may be combined with each other without limitation. Specifically, the acid value of the water-soluble polyurethane resin may be 10 mg KOH / g to 30 mg KOH / g, or 10 mg KOH / g to 25 mg KOH / g.

[0111] When the acid value of the water-soluble polyurethane resin satisfies the above range, excellent quick-drying properties, interlayer penetration prevention properties, leveling properties, etc. can be obtained. In particular, when the acid value of the water-soluble polyurethane resin is 10 mg KOH / g or more, the reaction with the curing agent including the isocyanate resin is improved by the hydroxyl group included in the structure, so that the adhesion and hardness of the coating film can be further improved even at temperatures below 100°C.

[0112] In addition, the number average molecular weight (Mn) of the water-soluble polyurethane resin may be 2,000 g / mol or more, 2,100 g / mol or more, 2,200 g / mol or more, 2,300 g / mol or more, 2,400 g / mol or more, or 2,500 g / mol or more. In addition, the number average molecular weight (Mn) of the water-soluble polyurethane resin may be 4,000 g / mol or less, 3,900 g / mol or less, or 3,800 g / mol or less.

[0113] Additionally, the weight average molecular weight (Mw) of the water-soluble polyurethane resin may be 10,000 g / mol or more, 11,000 g / mol or more, or 12,000 g / mol or more. The weight average molecular weight (Mw) of the water-soluble polyurethane resin may be 50,000 g / mol or less, 40,000 g / mol or less, or 30,000 g / mol or less.

[0114] Additionally, the polydispersity index (PDI, Mw / Mn) of the water-soluble polyurethane resin may be 2.0 to 5.0 or 2.0 to 4.0.

[0115] When the above number average molecular weight (Mn), weight average molecular weight and polydispersity index all satisfy the above ranges, high gloss can be achieved and there is an effect of improving high appearance and durability.

[0116] The above water-soluble polyurethane resin preferably has a solid content of 30 wt% to 50 wt% based on the total weight of the resin.

[0117] In addition, the water-soluble polyurethane resin may be included in an amount of 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, or 15 parts by weight or more, based on 100 parts by weight of the main component. In addition, the water-soluble polyurethane resin may be included in an amount of 20 parts by weight or less, 19 parts by weight or less, or 18 parts by weight or less, based on 100 parts by weight of the main component. The above numerical ranges may be combined with each other without limitation. Specifically, the water-soluble polyurethane resin may be included in an amount of 12 to 20 parts by weight, or 15 to 20 parts by weight, based on 100 parts by weight of the main component.

[0118] When the content of the water-soluble polyurethane resin is 12 parts by weight or more, excellent wettability, chemical resistance (solvent resistance), adhesion, water resistance, impact resistance, and chipping resistance can be secured, and the curing property of the coating film can be improved at a temperature of 100°C or lower by reacting with the curing agent. In addition, when the content of the water-soluble polyurethane resin is 20 parts by weight or less, a decrease in gloss and a decrease in the physical properties of the entire coating can be prevented.

[0119]

[0120] 5) Solvent

[0121] The subject matter of the present invention may additionally include a solvent.

[0122] The above solvent is a component that improves the workability of the composition by adjusting the viscosity of the composition, and can be appropriately selected and used depending on the characteristics or volatilization rate of the resin included in the composition, and can include either distilled water or an organic solvent.

[0123] Examples of the organic solvent that can be used include ester solvents such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, propylene glycol methyl ether acetate, and ethyl ethoxypropionate; alcohol solvents such as 2-ethyl hexanol, iso-butanol, n-butanol, propanol, and 1-methoxy-2-propanol; ether solvents such as ethylene glycol monobutyl ether (butyl cellosolve, manufactured by Shell) or ethylene glycol monohexyl ether (hexyl cellosolve, manufactured by Shell); or ketone solvents such as methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, and ethyl propyl ketone.

[0124] The solvent may be included in an amount of 40 parts by weight or more, 45 parts by weight or more, or 50 parts by weight or more, based on 100 parts by weight of the acrylic dispersion resin. In addition, the solvent may be included in an amount of 60 parts by weight or less, 55 parts by weight or less, or 53 parts by weight or less, based on 100 parts by weight of the acrylic dispersion resin.

[0125] When the above solvent content is within the above range, it has the effect of improving the painting workability.

[0126]

[0127] 6) Additives

[0128] In the present invention, in addition to the components included in the above-mentioned subject matter, additives conventionally used in water-soluble paint compositions can be additionally blended and used.

[0129] The above additives may further include at least one additive selected from the group consisting of a neutralizing agent, a pigment, a curing accelerator, a dispersant, a wetting agent, a thickener, a preservative, and an anti-foaming agent (typical amine neutralizing agents such as N,N-dimethylethanolamine and monoethanolamine), an anti-settling agent, and a pH adjusting agent.

[0130] The above additive may be included in an amount of 10 parts by weight or less, specifically 0.1 parts by weight to 10 parts by weight, or 0.1 parts by weight to 8 parts by weight, based on 100 parts by weight of the main component.

[0131]

[0132] B. Hardener

[0133] 1) Isocyanate resin

[0134] The water-soluble paint composition of the present invention may include a curing agent capable of curing the composition.

[0135] The above curing agent is a component that can form a urethane bond by reacting with a hydroxyl group of an acrylic dispersion resin or an acrylic emulsion resin in a paint composition to cure the composition, and may include an isocyanate resin.

[0136] Specifically, the isocyanate resin is not particularly limited in type as long as it does not cause yellowing, but may include, for example, hexamethylene diisocyanate, 1,6-diisocyanatohexane homopolymer, 4,4'-dicyclohexyl methane diisocyanate, tetramethyl xylene diisocyanate, or a mixture thereof.

[0137] In addition, the isocyanate resin may have a viscosity at 25°C of 1,500 cps or more, 2,000 cps or more, or 2,500 cps or more. In addition, the isocyanate resin may have a viscosity at 25°C of 7,500 cps or less, 6,500 cps or less, or 5,000 cps or less. When the viscosity at 25°C of the isocyanate resin is within the above range, the leveling and wetting properties of the paint are improved, and when the solid content is within the above range, the impact resistance, chipping resistance, and bending properties of the produced coating film are improved.

[0138] Additionally, the isocyanate resin may have a solid content of 70 to 80 wt%, or 72 to 78 wt%, based on the total weight of the resin.

[0139] Furthermore, the isocyanate resin may be included in an amount of 150 to 300 parts by weight, or 200 to 300 parts by weight, based on 100 parts by weight of the acrylic dispersion resin. When the content of the isocyanate resin is within the above range, the appearance characteristics of the produced coating film, particularly gloss, and mechanical properties are improved.

[0140]

[0141] 2) Solvent

[0142] The curing agent of the present invention may additionally contain a solvent.

[0143] The above solvent is a component that improves the workability of the composition by adjusting the viscosity of the composition, and can be appropriately selected and used depending on the characteristics or volatilization rate of the resin included in the composition.

[0144] Specifically, the solvent may include at least one of distilled water and an organic solvent.

[0145] The above organic solvent may be the same as or different from the organic solvent of the subject matter.

[0146] Specifically, the organic solvent may be, as representative examples, an ester solvent such as methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, propylene glycol methyl ether acetate, and ethyl ethoxypropionate; an alcohol solvent such as 2-ethyl hexanol, iso-butanol, n-butanol, propanol, and 1-methoxy-2-propanol; an ether solvent such as ethylene glycol monobutyl ether (butyl cellosolve, manufactured by Shell) or ethylene glycol monohexyl ether (hexyl cellosolve, manufactured by Shell); or a ketone solvent such as methyl ethyl ketone, methyl propyl ketone, methyl butyl ketone, and ethyl propyl ketone.

[0147] The above solvent may be included in an amount of 30 to 50 parts by weight, or 35 to 50 parts by weight, based on 100 parts by weight of the isocyanate resin. When the solvent content is within the above range, it has the effect of improving the painting workability.

[0148]

[0149] As described above, the water-soluble paint composition according to the present invention contains, as essential components, an acrylic dispersion resin containing a unit derived from polyalkylene glycol mono(meth)acrylate in an amount of 5 wt% to 13 wt% and a water-soluble polyurethane resin having an acid value of 10 mg KOH / g to 30 mg KOH / g, thereby being curable at a low temperature of 100°C or lower, or 90°C or lower. In addition, by applying the water-soluble paint composition, a coating film capable of securing excellent appearance characteristics and mechanical properties can be formed. Therefore, the water-soluble paint composition according to the present invention is not only suitable as a paint for intermediate painting of automobile parts and bodies, but also can reduce volatile organic compounds during the painting process and secure environmentally friendly and economical advantages.

[0150]

[0151] Hereinafter, the present invention will be described in more detail through examples. However, these examples are provided solely to aid understanding of the present invention and are not intended to limit the scope of the present invention in any way.

[0152] Example

[0153] I. Preparation of acrylic dispersion resin

[0154] Butyl cellosolve (Dow, Butyl Cellosolve solvent) and epoxy-containing ester monomer (Hexion, Cardura E10P) were mixed as a reaction solvent, the reaction mass was heated to 150°C, and then a primary polymerization initiator (tert-butyl peroxide (Cegi Arkema, Luperox 26)) was added to the reaction mass.

[0155] Next, in the presence of a primary polymerization initiator, 2-hydroxymethyl(meth)acrylate (ROHM, Meracyl® HEMA 98), an ethylenically unsaturated monomer and a hydroxyl group-containing acrylic monomer, and polyalkylene glycol mono(meth)acrylate monomer (NoF, Blemmer AP400) were additionally added dropwise and stirred for 1 hour. At least two of styrene (Yeocheon NCC, Styrene monomer), acrylic acid (LG Chem, Acrylic acid), normal butyl acrylate (LG chem), and methyl(meth)acrylate (LX MMA) were used as the ethylenically unsaturated monomer.

[0156] Next, a secondary polymerization initiator (tetrabutyl peroxide) was additionally added dropwise, cooled to 50°C, dimethylethanolamine (BASF, N,N-Dimethylehanolamine S) was added as a neutralizer, and distilled water was added dropwise for one hour while stirring. Finally, dibutyltin dilaurate (SONGCAT DBTO, Songwon) was additionally added as a curing accelerator, stirred for 10 minutes, and then the reactant was cooled to 40°C to terminate the reaction, thereby producing an acrylic dispersion resin. At this time, each component was mixed in the composition ratio as shown in Table 1 below.

[0157] Additionally, the physical properties of the manufactured acrylic dispersion resin are shown in Tables 2 and 3 below.

[0158]

[0159]

[0160]

[0161] Ingredients Manufacturing Example 1 Manufacturing Example 2 Manufacturing Example 3 Manufacturing Example 4 Manufacturing Example 5 Glass Transition Temperature (Tg) 35.3 35.0 35.0 35.2 Hydroxygen Value (OHv, mg KOH / g) 120 120 120 120 120 Viscosity (RVT #5 50 rpm) 1,600 1,500 1,580 1,510 1,640 Acid Value (mg KOH / g) 10 10 10 10 10 Particle Size (nm) 145 140 142 144 150 Number Average Molecular Weight 9,000 8,000 8,500 8,100 9,400 Weight Average Molecular Weight 19,000 18,000 18,600 18,500 19,500

[0162]

[0163] Comparison of ingredients Manufacturing example 1 Comparison Manufacturing example 2 Comparison Manufacturing example 3 Comparison Manufacturing example 4 Glass transition temperature (Tg) 35.3 24.5 35.1 34.1 Hydroxygen value (OHv, mg KOH / g) 120 120 120 120 Viscosity (RVT #5 50 rpm) 1,540 2,100 1,460 1,700 Acid value (mg KOH / g) 10 10 10 10 Particle size (nm) 14 2 14 7 14 2 15 1 Number average molecular weight 7,000 12,000 7,500 9,500 Weight average molecular weight 17,000 24,000 17,900 23,000

[0164]

[0165] II. Preparation of water-soluble paint composition

[0166] At room temperature (25℃), each of the acrylic dispersion resins manufactured in Manufacturing Examples 1 to 5 and Comparative Manufacturing Examples 1 to 4 was added to distilled water and butyl cellosolve as solvents, and then sequentially polyester resin, acrylic emulsion resin, and water-soluble polyurethane resin were added and stirred to homogenize, and then additives were added and stirred to prepare a main component. Then, an isocyanate-based resin and a hardener component including a solvent (butyl acetate) were added to the main component to prepare a water-soluble paint composition. At this time, the product name, ingredients, physical properties, etc. of each component used in the examples and comparative examples are shown in Table 4 below. In addition, each component was mixed in a composition ratio as described in Table 5 below to prepare the composition.

[0167] Ingredients Manufacturer / Product Name Properties Polyester Resin KCC Co., Ltd. / CRF00798 Glass Transition Temperature = -7℃, Acid Value = 28 mg KOH / g, Hydroxyl Value = 85 mg KOH / g, Polydispersity Index (PDI) = 2.1, Number Average Molecular Weight (Mn) = 1,700 g / mol, Weight Average Molecular Weight (Mw) = 3,800 g / mol Acrylic Emulsion Resin KCC Co., Ltd. / CHW00543 Glass Transition Temperature = -7℃, Acid Value = 12 mg KOH / g, Hydroxyl Value = 6 mg KOH / g, Polydispersity Index (PDI) = 3.7, Number Average Molecular Weight (Mn) = 30,000 g / mol, Weight Average Molecular Weight (Mw) = 100,000 g / mol, Viscosity = 200-500 cps, particle size (nm) = 100-150 Water-soluble polyurethane resin KCC Co., Ltd. / HU7003A Glass transition temperature = -10℃, acid value = 20 mg KOH / g, hydroxyl value = 80 mg KOH / g, polydispersity index (PD) = 3.7, number-average molecular weight (Mn) = 3,100 g / mol, weight-average molecular weight (Mw) = 11,000 g / mol, viscosity = 100-800 cps, particle size (nm) = 30-80 Butyl cellosolve Dow - neutralizer (Dimethylamino-2-ethanol; DMEA) Songwon - pigment TiO2 - dispersant BYK / BYK-190 - wetting agent BYKETOL-WS - thickener Acrosol RM8W - preservative Acticide BW-10-Foamex810-

[0168]

[0169]

[0170]

[0171] Experimental example

[0172] III. Evaluation of the characteristics of the coating

[0173] Using a spray gun, the water-soluble paint compositions of each example and comparative example were applied to the substrate on which the automotive electroplating coating was applied in a film thickness of 20 to 22 μm to perform an intermediate coating, and cured at 90°C for 20 minutes. Subsequently, the surface of the intermediate coating was sequentially subjected to an automotive topcoat and a clear coat. The physical properties of the resulting final coating film were measured using the following methods, and the results are shown in Table 6.

[0174] Specifically, the above intermediate coating was performed using a hand gun spray (nozzle diameter: 1.5 mm, air pressure: maintained at a constant level of approximately 4.5 kgf / ㎠), and moving horizontally at a speed of 40-50 cm / sec while maintaining a constant distance of 30 cm between the nozzle inlet and the specimen.

[0175] (1) Appearance

[0176] The LW value of the final coating was measured using an automotive exterior measuring device, Wave Scan DOI (BYK Gardner), after painting. A lower LW value of 10 or less indicates a better appearance.

[0177] (2) Adhesiveness

[0178] The surface of the final coating was made into 100 squares measuring 2 mm wide and 2 mm long with a knife, and then a transparent tape compression test was performed to remove the squares to evaluate the adhesion. The above adhesion evaluation was performed a total of 4 times, and the average value was calculated. At this time, if 100% of the 100 squares were completely attached, it was indicated as M-1 (very good), if 70% or more but less than 100%, it was indicated as M-2 (good), if 50% or more but less than 70%, it was indicated as M-3 (average), if 30% or more but less than 50%, it was indicated as M-4 (poor), and if less than 30%, it was indicated as M-5 (very bad).

[0179] (3) Hardness

[0180] Hardness was evaluated according to the method specified in MS652-09. Specifically, a pencil lead was attached to the surface of the final coating at a 45° angle, and then pressed horizontally at a speed of 0.5-1 mm / s for a distance of 7 mm while applying a load of 750 g, and the presence or absence of a trace was visually checked. The hardness of the hardest pencil that did not produce a trace was designated as the pencil hardness, and its value was indicated (hardness: 2H > H > F > HB > B > 2B). If the hardness measurement result is HB or higher, it is considered to be fully cured.

[0181] (4) Impact resistance

[0182] Impact resistance was evaluated using the method specified in MS652-09. Specifically, impact resistance was evaluated by measuring the height at which the coating was broken when a 500 g weight was dropped on the specimen while varying the drop height from 30 cm to 50 cm.

[0183] (5) Content

[0184] The content resistance was evaluated according to the method specified in MS653-01. Specifically, a cotton cloth sufficiently soaked in xylene solvent was placed on the surface of the final coating, and the surface was scratched four times with a fingernail at a force of 2 kgf per minute to measure the time it took for the base coating to appear.

[0185] (6) Water resistance

[0186] After leaving it at 40℃ for 10 days, the water resistance was evaluated by evaluating the adhesion according to the method specified in MS653-01. At this time, if the condition of the coating film was very good after leaving it for 10 days, it was indicated as M-1 (very good), if it was damaged by 80% or more but less than 100%, it was indicated as M-2 (good), if it was damaged by 60% or more but less than 80%, it was indicated as M-3 (average), if it was damaged by 30% or more but less than 60%, it was indicated as M-4 (poor), and if it was damaged by less than 30%, it was indicated as M-5 (very bad).

[0187] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Appearance (LW: 10 or less) 9.09.09.29.112.710.711.510.99.1 Adhesion (M-2 or less) M-1M-1M-1M-1M-2.5M-2.5M-2.5M-2 Hardness (HB or more) FHBHBHBHBHFBB Impact resistance (30 cm or more) 606060606020605050 Solvent resistance (5 minutes or more) 5↑5↑5↑5↑5↑5↑5↑5↑5↑5↑Water resistance (M-2 or less) M-1M-1M-1M-4M-2.5M-2.5M-2.5M-2

[0188]

[0189] Looking at Table 6 above, it can be confirmed that the coating films manufactured from the coating compositions of Examples 1 to 4 are excellent in appearance properties, adhesion, hardness, impact resistance, solvent resistance, and water resistance.

[0190] Meanwhile, in the case of the coating film manufactured from the paint composition of Comparative Example 1, the curing reactivity at low temperatures was reduced due to the use of the acrylic dispersion resin of Manufacturing Example 5, which was manufactured without using a curing accelerator, and thus, it was found that the appearance characteristics, adhesion, hardness, impact resistance, solvent resistance, and water resistance were inferior to the coating films manufactured from the paint compositions of Examples 1 to 4.

[0191] In addition, it can be seen that the coating film manufactured from the coating composition of Comparative Example 2 including the acrylic dispersion resin of Comparative Manufacturing Example 1 that does not include a unit derived from polyalkylene glycol mono(meth)acrylate is inferior in appearance properties, adhesion, impact resistance, and water resistance compared to the coating films manufactured from the coating compositions of Examples 1 to 4.

[0192] In addition, as the propylene glycol groups of the paint compositions of Comparative Examples 3 and 5, which each include the acrylic dispersion resin of Comparative Manufacturing Example 2 or Comparative Manufacturing Example 4 having a somewhat high unit content derived from polyalkylene glycol mono(meth)acrylate, increase and thus the hydrophilicity increases, the water resistance and adhesion decrease. Therefore, it can be seen that the coating films manufactured from the paint compositions of Comparative Examples 3 and 5 are inferior to the coating films manufactured from the paint compositions of Examples 1 to 4 in terms of appearance characteristics, adhesion, impact resistance, and water resistance.

[0193] In addition, it can be seen that the coating film manufactured from the coating composition of Comparative Example 4 having a somewhat lower unit content derived from polyalkylene glycol mono(meth)acrylate is significantly inferior in appearance properties, adhesion, hardness, impact resistance, and water resistance compared to the coating films manufactured from the coating compositions of Examples 1 and 2.

Claims

1. A subject matter comprising an acrylic dispersion resin comprising a unit derived from polyalkylene glycol mono(meth)acrylate; a polyester resin; an acrylic emulsion resin; and a water-soluble polyurethane resin; and Contains a curing agent containing an isocyanate resin, A water-soluble paint composition in which the content of units derived from the polyalkylene glycol mono(meth)acrylate is 5 to 13 wt% based on the total weight of monomers contained in the acrylic dispersion resin.

2. In paragraph 1, A water-soluble paint composition wherein the acrylic dispersion resin has a glass transition temperature (Tg) of 20°C to 60°C, a hydroxyl value (OHv) of 80 mg KOH / g to 150 mg KOH / g, an acid value (Av) of 9 mg KOH / g to 25 mg KOH / g, a number average molecular weight of 5,000 g / mol to 10,000 g / mol, and a weight average molecular weight of 10,000 g / mol to 20,000 g / mol.

3. In paragraph 1, A water-soluble paint composition wherein the acrylic dispersion resin further comprises at least one of a unit derived from an epoxy-containing ester monomer, a unit derived from an ethylenically unsaturated monomer, and a unit derived from a hydroxyl group-containing acrylic monomer.

4. In paragraph 1, A water-soluble paint composition wherein the water-soluble polyurethane resin has an acid value of 10 mg KOH / g to 30 mg KOH / g.

5. In paragraph 1, The water-soluble paint composition comprises, with respect to 100 parts by weight of the main component, 15 to 30 parts by weight of an acrylic dispersion resin, 2 to 10 parts by weight of a polyester resin, 1 to 5 parts by weight of an acrylic emulsion resin, and 12 to 20 parts by weight of a water-soluble polyurethane resin.

6. In paragraph 1, The above water-soluble paint composition is a water-soluble paint composition having a complete curing time of 20 minutes or less at 100°C or less.

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