KR20170086151A - Multilayer coating and molded article comprisng the same - Google Patents

Abstract

The present invention relates to a multi-layer coating which uses less VOC compared to existing solvent-based paints and can ensure excellent appearance, adhesion, water resistance and weather resistance even under the relatively short conditions of conventional hot air blowing and a molded article containing the same .

Description

TECHNICAL FIELD [0001] The present invention relates to a multi-layer coating and a molded article including the multi-

The present invention relates to multilayer coatings and molded articles comprising them.

In the case of automobile bumper paint, it is common to paint with EMPP (Elastomer Modified Polypropylene) based material and multi-layer coating consisting of primer-base coat-clear coat and painted with oil paint for each layer. The demand for water-based paints is on the rise.

When a water-soluble paint is applied, a hot air blow section for drying the moisture in the coat film is indispensably required in order to secure the necessary appearance and physical properties of the coating film. In the conventional paint line, 10 to 15 minutes, and thus the physical properties of the coating film are markedly lowered under a short hot air blowing condition

 Korean Patent Laid-Open Publication No. 2006-0078973 discloses a undercoating composition for automobile bumpers which can improve adhesion, filling property and abrasion property by including a chlorinated polyolefin-modified acrylic resin and a chlorinated polyolefin resin or the like , There is still a problem that the physical properties of the coating film are lowered under short hot air blowing conditions.

The present invention relates to a multi-layer coating which uses less VOC compared to existing solvent-based paints and can ensure excellent appearance, adhesion, water resistance and weather resistance even under the relatively short conditions of conventional hot air blowing and a molded article containing the same The technical problem is to provide.

The multilayer coating of the present invention comprises a primer coating layer made of a first composition comprising a water-dispersed polyolefin emulsion resin, an acrylic emulsion resin (A), a water-dispersed polyurethane resin (A) and a pigment; And a base coating layer made of a second composition comprising an acrylic emulsion resin (B), a water-dispersed polyurethane resin (B) different from the water-dispersed polyurethane resin (A) and a pigment, wherein the water- The resin (A) and the water-dispersed polyurethane resin (B) are each independently a mixture of two or more water-dispersed polyurethane resins.

The molded article of the present invention comprises the multilayer coating.

The multilayered coating of the present invention comprises an acrylic emulsion resin for improving the appearance and workability of the coating film and an aqueous dispersion type polyurethane resin for improving the physical properties of the coating film and the content of VOC is smaller than that of the conventional solvent- Is applied to a molded article such as an automobile bumper, it is possible to secure excellent appearance and adhesion, water resistance, weather resistance, and reinforcement even under the conditions of a conventional hot air blowing zone or relatively short time.

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

The multilayer coating of the present invention comprises a primer coating layer made of a first composition comprising a water-dispersed polyolefin emulsion resin, an acrylic emulsion resin (A), a water-dispersed polyurethane resin (A) and a pigment; (A) and a water-dispersed polyurethane resin (B), and a second coating composition comprising a water-dispersible polyurethane resin (A) and an acrylic emulsion resin (B) B) are each independently a mixture of two or more water-dispersed polyurethane resins.

The acrylic emulsion resin (A) of the first composition is different from the acrylic emulsion resin (B) of the second composition, and similarly the water-dispersed polyurethane resin (A) of the first composition is an aqueous dispersion polyurethane resin ).

The multilayered coating of the present invention can provide excellent appearance and adhesion, water resistance, weather resistance, and re-coatability, including a primer coating layer made of the first composition and a base coating layer made of the second composition. The multilayer coating can be applied, for example, in the form of a multilayer coating of a water-soluble primer-water-soluble basecoat-oil-resistant creover coat to an EMPP-based material for automotive bumpers.

That is, the use of an acrylic emulsion resin for improving the appearance and workability of a coating film and an aqueous polyurethane resin for improving physical properties of a coating film are used, It is possible to secure excellent appearance and adhesion, water resistance and weather resistance even under the conditions, and hydrolysis of the coating film can be prevented particularly under water-resistant conditions.

The first composition

The first composition capable of producing the primer coating layer comprises 25 to 30% by weight of the water-dispersed polyolefin emulsion resin, 5 to 10% by weight of the acrylic emulsion resin (A), a water-dispersed polyurethane resin ( A) 10 to 15 wt%, pigment 3 to 10 wt%, solvent 5 to 10 wt%, and ion exchange water 25 to 35 wt%.

The water-dispersed polyolefin emulsion resin is used for improving physical properties such as adhesion of material and water resistance, and may preferably be a chlorinated free water-dispersed olefin. Although not particularly limited, the water-dispersed polyolefin emulsion resin may have a solid content of 20 to 35% based on the total weight and a weight average molecular weight of 60,000 to 80,000. When the amount of the water-dispersible polyolefin resin is less than 25% by weight, the adhesion of the material and the water resistance of the polyolefin resin are less than 100% by weight based on the total weight of the first composition. If the amount is more than 30% by weight, There is a problem that the appearance is deteriorated.

The acrylic emulsion resin (A) is used for the purpose of improving appearance and workability, and is not particularly limited, but the acrylic emulsion resin has a solid content of 30 to 50% based on the total weight and a glass transition temperature (Tg) of 60 to 80 Lt; 0 > C can be used.

The first composition may comprise 5 to 10% by weight of the acrylic emulsion resin (A). When the content is less than 5% by weight, appearance and workability are poor. When the content is more than 10% by weight, physical properties of coating film, particularly, water resistance may be deteriorated. Here, the acrylic emulsion resin may be a copolymer in which an ethylenically unsaturated acrylic monomer and a monoethylenic-unsaturated acid monomer are mixed and is not particularly limited. For example, acrylic monomers include methyl acrylate, ethyl acrylate, butyl acrylate (Meth) acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, aminoalkyl (meth) acrylate, hydroxyethyl methacrylate, (Meth) acrylate monomer such as N, N-dialkylaminoalkyl (meth) acrylate, N-alkylaminoalkyl (methacrylate), N, N-dialkylaminoalkyl (meth) acrylate, The systematic-unsaturated acid monomer is selected from the group consisting of acrylic acid, methacrylic acid, crotonic acid, itaconic acid, sulfoethyl methacrylate, It may include a unsaturated acid monomer 0.5-30% by weight butyl methacrylate, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, and maleic anhydride, such as, monoethylenically.

The water-dispersed polyurethane resin (A) of the present invention is included for realizing excellent coating film properties, and is not particularly limited, but the water-dispersed polyurethane resin (A) is a mixture of two or more kinds such as polyether polyurethane resin, poly From a group consisting of an ester polyurethane resin, a polycarbonate polyurethane resin, a polyetherester polyurethane resin, a polyether carbonate polyurethane resin, a polycaprolactone polyurethane resin, a hydrocarbon polyurethane resin, an aliphatic polyurethane resin and an aromatic polyurethane resin You can use what is selected.

The water-dispersed polyurethane resin (A) of the present invention can be used in an amount of 35 to 55% by weight based on the total weight of solid components, for example, a weight average molecular weight of 45,000 to 55,000, a pH of 6 to 9, A polyester polyurethane resin (a) having a solid content of 45 to 55%, a glass transition temperature of -10 to 10 占 폚, a pH of 6 to 8 And a polyester polyurethane resin (b). For example, the mixing ratio of the polyurethane resin (a) and the polyurethane resin (b) may be 1: 0.4 to 1: 1.6 on a weight basis.

The first composition comprises 10 to 15% by weight of the water-dispersible polyurethane resin (A) based on 100% by weight of the total composition. When the content of the water-dispersed polyurethane resin (A) is less than 10% by weight, the water resistance is deteriorated. When the content of the water-dispersed polyurethane resin (A) exceeds 15% by weight,

The first composition of the present invention may include pigments for color implementation and is not particularly limited, but may be selected from the group consisting of aluminum paste, mica, titanium dioxide, carbon black, extender pigments, organic pigments and combinations thereof . These pigments can be used in common for the first composition and the second composition.

The pigment contains 3 to 10% by weight based on 100% by weight of the first composition. When the content of the pigment is too small, it is difficult to obtain a proper color hiding and hiding power. When the content of the pigment is too large, Can fall.

The solvent may comprise 5 to 10% by weight, based on 100% by weight of the total composition. When the content of the solvent is too low, the wettability of the material is poor. On the other hand, when the content of the solvent is too large, the VOC content is exceeded.

Although not particularly limited, examples of the solvent include butyl glycol, hydrocarbons, alcohols, and combinations thereof. Such a solvent can be commonly used for the first composition and the second composition.

The ion-exchanged water may contain 25 to 35% by weight, based on 100% by weight of the first composition. When the content of the ion-exchanged water is too low, there is a problem that the coating workability is poor. On the contrary, when the content is too large, the film may remain after passing through hot air blowing, thereby deteriorating the physical properties of the coating film.

The composition of the present invention may further comprise at least one additive selected from the group consisting of a surface lubricant, a thickener, a surface modifier, a defoamer, an antisettling agent, a neutralizing agent and a UV additive. For example, as the surface lubricant, a polyether siloxane surface lubricant or the like can be used. As the thickener, a modified acrylic polymer thickener or the like can be used. As the surface adjusting agent, an ethoxylate polymer surface modifier or the like can be used. As the antifoaming agent, a polysiloxane antifoaming agent or the like may be used.

Although not particularly limited, the content of the additive may be 0.1 to 10% by weight based on 100% by weight of the composition. Such additives may be commonly used for the first composition and the second composition.

The second composition

The second composition of the present invention comprises 10 to 15% by weight of the acrylic emulsion resin (B), 25 to 35% by weight of the water-dispersed polyurethane resin (B), 1 to 10% by weight of the pigment, 10 to 20% by weight and ion exchange water 20 to 40% by weight.

The second composition of the present invention includes an acrylic emulsion resin for improving the appearance and workability of the coating film. The acrylic emulsion resin has a molecular weight (Mw) of 30,000 to 50,000 and a solid content of 35 to 50% , And a glass transition temperature (Tg) of -15 to 0 占 폚.

The acrylic emulsion resin (B) comprises 10 to 15% by weight, for example 12 to 15% by weight, based on 100% by weight of the total composition. When the content of the acrylic emulsion resin is more than 15% by weight, the coating film properties, particularly, the water resistance are deteriorated. When the content is less than 10% by weight, the workability of the coating agent is deteriorated.

The second composition of the present invention comprises a water-dispersed polyurethane resin (B) for realizing excellent coating film properties. The water-dispersed polyurethane resin (B) is a mixture of two or more kinds, for example, has a weight average molecular weight of 45,000 to 55,000, a pH of 6 to 9, a viscosity of 40 to 600 mPa.s and a solid content of 49 to 51 %, A glass transition temperature of 10 to 30 占 폚, a solid content of 35 to 45%, a pH of 7 to 9, and a viscosity of 30 to 40 lt; RTI ID = 0.0 > mPa · s. < / RTI > Preferably, the mixing ratio of the polyurethane resin (a) and the polyurethane resin (c) may be 1: 1 to 1: 1.2 on a weight basis.

The water-dispersible polyurethane resin (B) comprises 25 to 35% by weight, for example 30 to 35% by weight, based on 100% by weight of the total of the second composition. When the content of the water-dispersed polyurethane resin (B) is less than 25% by weight, the water resistance is deteriorated. When the content of the water-dispersed polyurethane resin (B) exceeds 35% by weight,

The pigment contains 1 to 10% by weight based on 100% by weight of the total amount of the second composition. If the content of the pigment is too small, it is difficult to obtain a proper color hiding and hiding power. If the content of the pigment is too large, Can fall.

The solvent may comprise from 10 to 20% by weight of the solvent, for example from 10 to 15% by weight, based on 100% by weight of the total composition. When the content of the solvent is too low, the wettability of the material is poor. On the other hand, when the content of the solvent is too large, the VOC content is exceeded.

The composition of the present invention may comprise 20 to 40% by weight, such as 20 to 30% by weight, of ion exchange water, based on 100% by weight of the total composition. When the content of the ion-exchanged water is too low, there is a problem that the coating workability is poor. On the contrary, when the content is too large, the film may remain after passing through hot air blowing, thereby deteriorating the physical properties of the coating film.

According to another aspect of the present invention, there is provided a molded article comprising the multilayered coating. The material of the molded article may be a polypropylene or ABS-based material, and may be used for an automobile part such as an automobile bumper.

Hereinafter, the present invention will be described more specifically by way of examples. However, these examples are provided only for the understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[Example]

One. Manufacturing example

Production Example 1-1. Preparation of first composition for primer coating layer

Acrylic emulsion resin A, water-dispersed polyurethane A, water-dispersed polyurethane B, and ion-exchanged water were placed in a container and mixed with stirring at a low speed (300 to 500 rpm) using a stirrer, and stirred for 10 minutes. Pigment, neutralizer, defoamer, quencher, and thickener were sequentially added while agitating the above materials, and the mixture was stirred at 1500 rpm at a high speed until the quencher satisfied the specified particle size (25 microns). Then, while stirring the above materials, ion-exchanged water, a polyolefin emulsion, a surface conditioner, a defoamer, a thickener and a neutralizer were added and stirred for 30 minutes. The viscosity was adjusted to 25 to 35 seconds by using a Ford cup (NO # 4) using ion-exchanged water as required (each component was mixed with a composition as shown in Table 1 below).

Production Example 1-2. Preparation of second composition for base coat layer

The acrylic emulsion resin B, the water-dispersed polyurethane A resin, the water-dispersed polyurethane C resin and the ion-exchanged water were put into a vessel and stirred at a low speed (300 to 500 rpm) using a stirrer while stirring with a UV additive and a solvent for 10 minutes Respectively. A separate container was charged with the aluminum paste and the solvent as pigments, stirred for 10 minutes, and then added to the mixed solution prepared above with stirring. A surface lubricant, a thickener, a surface conditioner, a defoamer, an anti-settling agent and a neutralizing agent were added while stirring the above materials, and the mixture was stirred for 10 minutes. Thereafter, the viscosity was adjusted to 30 to 35 seconds by using a pod cup (NO # 4) using ion-exchanged water (each component was mixed with a composition as shown in Table 1 below).

Polyolefin emulsion: solid content 30%, weight average molecular weight (Mw) 60,000 to 80,000 (TOYOBO)

Acrylic emulsion resin A: solid content 45%, glass transition temperature (Tg) 70 ° C

Acrylic emulsion resin B: solid content 45%, glass transition temperature (Tg) -6 캜, weight average molecular weight 40,000 to 45,000

Water-dispersed polyurethane resin A: weight average molecular weight (Mw) 45,000 to 55,000, solid content 50%

Water-dispersed polyurethane resin B: solid content 50%, glass transition temperature (Tg) 0 C

Dispersed polyurethane resin C having a solid content of 35%, a glass transition temperature (Tg) of 20 to 30 占 폚, a molecular weight distribution of 20,000 to 30,000, a viscosity of 30 to 40 cps (KCC)

Pigment A: Titanium dioxide and carbon black

Pigment B: Aluminum paste

Solvent: butyl glycol

Surface Conditioning Agent: Ethoxylate polymer surface modifier (BYK)

Thickening agent: modified acrylic polymer thickener (BASF)

Defoamer: Polysiloxane defoamer (Airproduct)

Quenching agent: synthetic silica (Fuji Silysia)

Neutralizer: Amine (ANGUS Chemie)

UV additive: Hydroxy phenyl benzotriazole based UV additive

Ion-exchange water

Surface lubricant: polyether siloxane-based (Tego)

Preparation Example 2. Preparation of a molded article comprising a multilayer coating made from the first and second compositions

(Dry film thickness: 15 to 20 microns), which was the second composition, after drying the primer (dry film thickness: 10 to 12 microns) of the first composition on a polypropylene substrate at 40 ° C for 4 minutes, , Dried at 65 ° C for 6 minutes, and left at room temperature for 10 minutes. A separately prepared clear coat (dry film thickness: 28 to 38 microns) was coated thereon to cure the final coating film by hot air at 80 DEG C for 30 minutes.

2. Results

The paint workability, appearance and physical properties of the final coating film were measured as follows, and the results are shown in Table 2 below.

1) Painting workability

IWATA was applied to a 30x40 cm tin plate twice for 61 reciprocating cycles to compare the degree of atomization and degree of smoothness of the coating and the degree of scratching.

2) Appearance

The paint was applied to a plastic substrate coated with a primer, and then dried at 80 ° C for 6 minutes. Then, a clear coat was applied thereon to compare bubbles, foreign matter, spots, grooves and smoothness of the surface.

3) Adhesiveness

Based on the ASTM D3359 tape adhesion test method, the degree of the peeled portion after the tape adhesion test among 100 pieces of 1 mm x 1 mm scale was observed.

4) Water resistance

After the coating film was immersed for 10 days in a 40 ° C thermostat, adhesion test and appearance evaluation were carried out.

5) High pressure washability

High - pressure water was sprayed at a pressure of 70 kgf at a distance of 10 cm with a prescribed high - pressure washing machine to compare the degree of peeling of the coating film.

6) Weatherability

The appearance, color difference, and adhesion of the film were compared after exposure to 2500 kJ energy in a Xenon weatherometer environment.

7) Re-construction

The original coating was repainted at intervals of 1 to 7 days to compare the appearance and adhesion of the coating.

As can be seen from Table 2, the multi-layer coatings of Examples 1 and 2 of the present invention were evaluated in terms of paint workability, appearance, adhesion, water resistance, high pressure washability and weatherability, but the acrylic emulsion resin Of Comparative Example 3 and Comparative Example 2 in which the content of the water-dispersed polyurethane resin was less than that of Comparative Example 3 and Comparative Example 4 in which the content of the acrylic emulsion resin or the water-dispersed polyurethane resin was less than that of Comparative Example 3 , It was found that it was poor in painting workability, re-coatability and appearance.

Therefore, when the multilayered coating of the present invention is applied to a molded article such as an automobile bumper, excellent appearance and adhesion, water resistance, and weather resistance can be secured even in the conventional hot air blowing zone or in a relatively short time.

Claims (9)

A primer coating layer made of a first composition comprising a water-dispersed polyolefin emulsion resin, an acrylic emulsion resin (A), a water-dispersed polyurethane resin (A) and a pigment; And
A base coat layer made of a second composition comprising an acrylic emulsion resin (B), a water-dispersed polyurethane resin (B) and a pigment,
The water-dispersed polyurethane resin (A) and the water-dispersed polyurethane resin (B) are each independently a mixture of two or more water-dispersed polyurethane resins. The composition according to claim 1, wherein the first composition comprises 5 to 10% by weight of an acrylic emulsion resin (A) and 10 to 15% by weight of an aqueous dispersion polyurethane resin (A), based on 100% . The composition according to claim 1, wherein the second composition comprises 10-15% by weight of acrylic emulsion resin (B) and 25-35% by weight of water dispersible polyurethane resin (B), based on 100% . The water-dispersed polyurethane resin (A) and the water-dispersed polyurethane resin (B) each independently have a weight average molecular weight of 45,000 to 55,000 and a solid content of 35 to 55% A multi-layer coating The multi-layer coating according to claim 1, wherein the water-dispersed polyolefin emulsion resin has a solid content of 20 to 35% and a weight average molecular weight (Mw) of 60,000 to 80,000. The water-dispersed polyurethane resin according to claim 1, wherein the water-dispersed polyurethane resin is selected from the group consisting of polyether polyurethane resin, polyester polyurethane resin, polycarbonate polyurethane resin, polyetherester polyurethane resin, polyether carbonate polyurethane resin, polycaprolactone polyurethane resin , A hydrocarbon polyurethane resin, an aliphatic polyurethane resin, and an aromatic polyurethane resin. The multi-layer coating of claim 1, wherein the pigment is selected from the group consisting of aluminum paste, mica, titanium dioxide, carbon black, extender pigments, organic pigments, and combinations thereof. The composition of claim 1, wherein the first composition and the second composition each independently comprise at least one additive selected from the group consisting of a surface lubricant, a thickener, a surface modifier, an antifoam, an antisettling agent, Multilayer coating. A molded article comprising the multilayer coating according to any one of claims 1 to 8.