KR20110043234A - Uv curable coating composition - Google Patents

Abstract

PURPOSE: A UV curable coating composition is provided to form a film with excellent abrasion resistance, high hardness, and high scratch resistance and to ensure excellent productivity. CONSTITUTION: A UV curable coating composition includes 20-50 parts by weight of a polyester acrylate oligomer of 6 functional group or more, 5-30 parts by weight of urethane acrylate oligomer of 2 functional group or more, 20-40 parts by weight of at least one photo-curable monomer, and 5-20 parts by weight of photoinitiator. The coating composition additionally includes a slip agent.

Description

CurUV curable coating composition

The present invention relates to a UV curable coating composition for forming abrasion resistance, high hardness, high scratch resistance coating film.

With the recent technological developments, as consumer demand for better products increases, the preference for products having a beautiful surface appearance and excellent selection is increasing.

By forming a coating film on various steel materials, surface protection, corrosion protection and material beauty can be provided. In general, in order to achieve the above object, a coated steel sheet and a laminated steel sheet have been mainly used, but both of these products require a high temperature drying equipment necessary for evaporation of a solvent during coating by a solvent-type thermal curing method.

UV coating method is able to work in a short time, so it is very productive, and it does not use solvents to reduce the environmental pollution problem, and other other coating methods such as solvent volatilized coating method, thermosetting type coating method, electrostatic and electrodeposition Energy-saving drying method with very low energy consumption because no heating process is required compared to the coating method and powder coating method. However, due to the UV curing method, the shrinkage is high and the curing density is high. Not suitable for metal coatings.

In addition, Korean Patent Nos. 10-0111128 and 10-0126366 disclose ultraviolet curing coating compositions for iron and metal. In order to apply to the steel sheet, the coating composition must have not only the physical properties described in the patent, but also corrosion resistance. In the composition of the patent, an inorganic anti-corrosive pigment is used to secure corrosion resistance, and thus it is not suitable for the transparent coating method required in the present invention. There is a problem, and there is a need to solve this problem as well as a transparent coating as well as a corrosion resistance and corrosion resistance, scratch resistance for corrosion prevention.

An object of the present invention relates to a UV-curable coating composition of abrasion resistance, high hardness, high scratch resistance, to solve the problems in the prior art and to solve the adhesion and shrinkage deformation of the steel material and difficult to implement in conventional general solvent coating It is to provide a coating composition excellent in wear resistance, high hardness, high scratch resistance.

More specifically, it is transparent coated on a general steel sheet, a coated steel sheet, or a Cr-free steel sheet, and then has excellent stiffness and abrasion resistance in terms of coating properties, and a pencil hardness of 8H or more to provide a UV-curable coating composition having excellent scratch resistance. It is.

It is also an object of the present invention to provide an environmentally friendly coating composition characterized by a solvent-free coating having 100% solids.

UV-curable coating composition for steel sheet should be excellent in physical properties such as appearance (transparent coating), sunscreen, corrosion resistance, scratch resistance and interlayer adhesion with the surface treatment agent.

Therefore, the selection of oligomers is important to produce a coating that can satisfy these properties. In the case of the polyester acrylate type of the oligomer, the aromatic type satisfies condensation, corrosion resistance, scratch resistance, and the like among the above properties, but was poor in weatherability during transparent coating and poor in steel sheet adhesion.

In addition, the aliphatic type, on the contrary, had good weather resistance and adhesion, but poor corrosion resistance, scratch resistance and the like.

Secondly, in the case of urethane acrylate, most of the above properties can be satisfied, but in the case of corrosion resistance, even if the surface treatment agent is coated on the undercoat, the urethane type alone cannot be satisfied.

Finally, the epoxy acrylate type is mostly manufactured based on a raw material called bisphenol A. When the bisphenol A type epoxy acrylate is used as it is, the crosslinking density of the coating film is high, and the chemical resistance, which is the main characteristic of the epoxy, is hard. The good physical properties such as goodness, corrosion resistance, scratch resistance, etc. can be satisfied, but the weathering is weak due to the yellowing occurs during the transparent coating is difficult to apply to the building materials exposed to the outdoors as the present invention.

Therefore, in the present invention, a polyester acrylate oligomer is used as the main base, and a polyester acrylate having 6 or more functional groups is used to increase corrosion resistance and scratch resistance, and exhibit excellent gloss, while using a bifunctional urethane acrylate. The present invention was completed by increasing the adhesion between the surface treatment agent and the UV curable coating composition having excellent processability and flexibility.

UV curable coating composition of the present invention is capable of forming a wear-resistant, high hardness, high scratch-resistant coating film, and is excellent in productivity by transparent coating on the steel sheet, it is environmentally friendly because no solvent is used. Therefore, it is particularly advantageous when used in a steel sheet which is excellent in wear resistance, good hardness and scratch resistance. In particular, when applying the UV-curing coating composition to the steel sheet, it is possible to save energy instead of the conventional thermosetting type, it is possible to reduce the cost maintenance cost.

The present invention relates to a UV curable coating composition comprising at least a 6 functional polyester acrylate oligomer, a bifunctional urethane acrylate oligomer, at least one photocurable monomer and a photoinitiator.

A polyester acrylate oligomer of 6 or more functional groups can be used. Specifically, one or more selected from commercially available Ebecryl 830 ™, 870 ™ (Cytec), CN 2295 ™, 2297 ™ (Sartomer), and Miramer PS610 ™ (Miwon Corporation) can be used. And, if the polyester acrylate oligomer having a six functional group or more can be used as a raw material of the UV-curable coating composition of the present invention.

The bifunctional urethane acrylate oligomer can be used. Specifically, at least one of UA-2205 ™, UA-2890BX ™, UA-5221 ™ (HS Chemtron), CN 966J75 ™, CN 966H90 ™ (Sartomer), Ebecryl 244 ™, and Ebecryl 284 ™ (Cytec) Although it can select and use, it is not limited to this, If it is a urethane acrylate oligomer which has a bifunctional group, it can be used without a restriction.

As the photocurable monomer, mono- or tri-functional acrylic monomers can be used, such as acrylic morpholine (ACMO), tetrahydroperfuryl acrylate (THFA), hydroxy ethyl acrylate (HEA), hydroxy propyl acrylate ( HPA), monofunctional acrylic monomers such as isobornyl acrylate (IBOA) and trimethylolpropane triacrylate, ethoxylated (3 mole) trimethylolpropane triacrylate, ethoxylated (6 mole) trimethylolpropane One or more of trifunctional acrylic monomers such as triacrylate, propoxylated (3 mole) trimethylolpropane triacrylate (TMPTA), pentaerythritol triacrylate (PETA) can be selected and used, but not limited thereto. Do not.

As the photoinitiator, a conventional polymerization initiator which is activated by ultraviolet rays is used. Examples of the polymerization initiator include benzophenone series, benzoin, benzoin ether series, benzyl ketal series, acetophenone series, anthraquinone series, and thi Compounds, such as an oxo xanthone type, are mentioned. These may be used alone or in combination of two or more, but are not limited thereto. Examples of commercially available polymerization initiators include Irgacure 184 ™, 754 ™, 819 ™, Darocur 1173 ™, TPO ™ (CIBA GEIGY), Micure CP-4 ™, MP-8 ™, BP ™, TPO ™ One or more of them may be selected and used, but is not limited thereto. However, in order to utilize the characteristics of the solvent-free UV coating agent which is the purpose of the present invention, it is preferable to use Irgacure 754 ™, Darocur 1173 ™, and Micure MP-8 ™, which are liquid initiators, in consideration of ease in manufacturing process.

The UV curable coating composition of the present invention may further comprise a slip agent, where the slip agent may also mean a leveling agent. They affect coating appearance, wear resistance and surface scratch resistance. And an additive selected from the group consisting of phosphate acrylate (acid value 250), polyether siloxane compound, and fluoroalkyl compound. In addition, commercially available TEGO Glide 405 ™, 410 ™, 432 ™, 435 ™, 440 ™, 450 ™, ZG400 ™, TEGO FLOW 300 ™, 370 ™, TEGO RAD 2100 ™, 2200N ™, 2250 ™, 2300 ™ , BYK-UV 3500 ™, 3510 ™, zonyl 8857 ™, 8867 ™ can be selected from, but is not limited to these.

The UV curable coating composition of the present invention may further include one or more additives selected from the group consisting of antifoaming agents and adhesion promoters, and appropriate additives may be selected and used as necessary.

The antifoaming agent is used to remove the bubbles generated during the roll coating process, and is used in TEGO ™, Airex 920 ™, 932 ™, 936 ™, 955 ™, 986 ™, BYK 088 ™, 1790 ™, AFCONA 2020 ™, 2021 ™, 2720 ™, 2725 ™ and 2038 ™ can be selected but are not limited to these.

In the UV curable coating composition of the present invention,

20 to 50 parts by weight of polyester acrylate oligomer of 6 or more functional groups, 5 to 30 parts by weight of bifunctional urethane acrylate oligomer, 20 to 40 parts by weight of one or more photocurable monomers, 5 to 20 parts by weight of photoinitiator, antifoaming agent, slip 0.1 to 1 part by weight of each, and 0.1 to 2 parts by weight of an adhesion promoter.

When less than 20 parts by weight of polyester acrylate oligomers having 6 or more functional groups are used, corrosion resistance and scratch resistance deteriorate. Therefore, the polyester acrylate oligomer of the six or more functional groups is preferably included in 20 to 50 parts by weight of the total coating composition.

When the bifunctional urethane acrylate oligomer is used in an amount less than 5 parts by weight, the coating film hardness is increased, resulting in poor workability and adhesion, and when used in excess of 30 parts by weight, the coating film hardness is lowered, resulting in poor scratch resistance. Accordingly, the bifunctional urethane acrylate oligomer is preferably included in the amount of 5 to 30 parts by weight of the total coating composition.

When the monofunctional reactive acrylic monomer is used at less than 20 parts by weight, the viscosity becomes high and the adhesion is poor. When the monofunctional reactive acrylic monomer is used in excess of 40 parts by weight, the UV curing becomes slow and productivity is a problem. Therefore, the monofunctional reactive acrylic monomer is preferably included in 20 to 40 parts by weight of the total coating composition.

When the trifunctional reactive acrylic monomer is used in less than 5 parts by weight, curing becomes slow and workability becomes a problem. If it exceeds 20 weight part, adhesiveness will worsen. Therefore, the trifunctional reactive acrylic monomer is preferably included in 5 to 20 parts by weight of the total coating composition.

If the photoinitiator is used in an amount less than 1 part by weight, the curing time of the coating coated on the steel sheet is increased and productivity is decreased, and if the content is used in excess of 20 parts by weight, the storage stability of the coating may be lowered. Therefore, the photoinitiator preferably contains 1 to 20 parts by weight.

The slip agent may include 0.1 to 1 parts by weight, and the antifoaming agent may include 0.1 to 1 parts by weight.

The adhesion promoter is an acrylic phosphate adhesion promoter. When the content of the adhesion promoter is less than 0.1 part by weight, the interlayer adhesion is significantly lowered. When the content is more than 2 parts by weight, the viscosity of the coating is increased to affect workability. Therefore, the adhesion promoter is preferably included in 0.1 to 2 parts by weight of the total coating composition.

Hereinafter, the present invention will be described in more detail with reference to examples according to the present invention and comparative examples not according to the present invention, but the scope of the present invention is not limited to the following examples.

[ Example ]

Example  One

35 g of polyester acrylate oligomer (CN 2295), 15 g of urethane acrylate oligomer (UA-2205), 30 g of isobornyl acrylate (IBOA), 10 g of trimethylolpropane triacrylate (TMPTA), 8 g of photoinitiator (Darocur 1173), 0.5 g of antifoaming agent Airex 920, 0.5 g of leveling agent and slip agent Glide 410, and 1 g of adhesion promoter were mixed to prepare a coating composition. The composition of the components used is shown in Table 1 below.

Example  2

34 g of polyester acrylate oligomer (Miramer PS610), 16 g of urethane acrylate oligomer (UA-2890BX), 30 g of tetrahydrofurfuryl acrylate (THFA), 10 g of pentaerythritol triacrylate (PETA), photoinitiator (Darocur 1173) A coating composition was prepared by mixing 8 g, antifoaming agent Airex 920 0.5g, leveling agent and slip agent Zonyl 8867 0.5g, and adhesion promoter 1g. The composition of the components used is shown in Table 1 below.

Example  3

36 g of polyester acrylate oligomer (Miramer PS610), 15 g of urethane acrylate oligomer (UA-5221), 30 g of tetrahydrofurfuryl acrylate (THFA), 11 g of trimethylolpropane triacrylate (TMPTA), photoinitiator (Irgacure 754) A coating composition was prepared by mixing 6 g, an antifoaming agent Airex 920 0.5 g, a leveling agent and a slip agent Rad 2250 0.5 g, and an adhesion promoter 1 g. The composition of the components used is shown in Table 1 below.

Comparative example  One

35 g of epoxy acrylate (Santomer's CN120), 15 g of urethane acrylate (UA-2890BX), 30 g of tetrahydrofurfuryl acrylate (THFA), 10 g of trimethylolpropane triacrylate (TMPTA), 8 g of photoinitiator (Darocur 1173) A coating composition was prepared by mixing 0.5 g of an antifoaming agent, Airex 920, 0.5 g of a leveling agent and a slip agent, Glide 410, and 1 g of an adhesion promoter. The composition of the components used is shown in Table 1 below.

Comparative example  2

35 g of urethane acrylate (Ebecryl 1290, 6 functional from CYTEC), 15 g of urethane acrylate oligomer (UA-2890BX), 10 g of tetrahydrofurfuryl acrylate (THFA), 10 g of trimethylolpropane triacrylate (TMPTA), photoinitiator (Darocur 1173) A coating composition was prepared by mixing 8 g, an antifoaming agent Airex 920 0.5 g, a leveling agent and a slipping agent Glide 410 0.5 g, and an adhesion promoter 1 g. The composition of the components used is shown in Table 1 below.

The compositions of Examples 1 to 3 and Comparative Examples 1 and 2 are summarized in Table 1.

[Table 1] Composition table

Example  One Example  2 Example  3 Comparative example  One Comparative example  2 CN 2295 35 Miramer PS610 34 36 CN 120 35 UA-2205 15 UA-2890BX 16 15 15 UA-5221 15 Ebecryl 1290 35 IBOA 30 THFA 30 30 30 30 TMPTA 10 11 10 10 PETA 10 Darocur 1173 8 8 8 Irgacure 754 8 6 Airex 920 0.5 0.5 0.5 0.5 0.5 Glide 410 0.5 Zonyl 8867 0.5 Rad 2250 0.5 0.5 0.5 Adhesion promoter One One One One One system 100 100 100 100 100

(Experimental method)

-UV curing: coated with a # 3 Bar coater (coating thickness of 3 ~ 5㎛) on the steel plate coated with the surface treatment agent to each UV-curable coating prepared according to Examples 1 to 3, Comparative Examples 1 and 2 Nitrogen was added (O ₂ concentration of 50 PPM or less), and then irradiated with UV (2000mJ / cm ² ) to cure.

(Property test method)

-Appearance: It was evaluated whether the appearance of the coated coating film was good without foreign matter and unpainted site.

(◎: no abnormality, ○: slight tee, Δ: some cratering, ×: many cratering and yellowing)

Abrasion resistance: The coated specimens were rotated 500 times at 250g load using a Taber abrasion tester according to ASTM D 4060-84 to evaluate the abrasion resistance. As the amount of wear increases, wear resistance decreases.

(◎: No abnormality, ○: Only wear traces are shown, △: Some wear occurs, ×: coating film peeling)

-Scratch resistance: The degree was measured by pencil hardness, pencil hardness was measured according to JIS K5600-5-4KS. (For reference, pencil hardness is evaluated as hardness in the following order, and the order is from 9B to 9H. The hardness is weaker toward 9B, and stronger toward 9H.)

-Adhesiveness: 100 coated coated specimens were made with a cutter to have a size of 1 mm, and 3M tape was attached and then peeled off to evaluate the adhesion of the coating film.

(◎: no abnormality, ○: less than 10 drops, △: less than 50 drops, x: complete dropout)

-Solvent resistance (MEK rubbing resistance): Rubbing the gauze in a reciprocating application of MEK on the gauze and applying a constant force to observe the coating state.

(◎: 50 or more times, ○: less than 20 times, △: less than 10 times, ×: less than 5 times)

Table 2 compares the coating properties according to the physical property test method.

[Table 2] Coating property comparison table

Exterior Wear resistance Scratch resistance
(Pencil hardness) Adhesion Solvent resistance
( MEK Rubbing castle) Example  One ◎ ◎ 8H ◎ ◎ Example  2 ◎ ◎ 8H ◎ ◎ Example  3 ◎ ◎ 8H ◎ ◎ Comparative example  One X △ 8H X ◎ Comparative example  2 ◎ △ 5H △ △

As shown in Table 2, in Examples 1 to 3 having a polyester acrylate oligomer of 6 or more functional groups as a main, most of the physical properties were satisfied in accordance with the spirit of the present invention. In particular, the wear resistance was excellent and the pencil hardness was 8H or more. Subsequently, even if it scratched with a coin, it was so hard that it was not scratched, and it was excellent in scratch resistance.

On the other hand, in the case of Comparative Example 1 mainly composed of epoxy acrylate oligomer, the coating film was considerably hard, so the scratch resistance was good, but the coating film was brittle, and the interlayer adhesion with the surface treatment agent was not good (the coating film was completely peeled off from the material). ), And also had the disadvantage of yellowing after UV curing (stripes were formed on the surface, which resulted in poor leveling), which makes it impossible to use as a coating.

Similarly, in Comparative Example 2, mainly composed of urethane acrylate oligomers, adhesion, scratch resistance, abrasion resistance, and adhesion were relatively poorer than polyester acrylates despite the use of a six-functional urethane acrylate.

Claims (7)

A UV curable coating composition comprising a polyester acrylate oligomer of at least six functional groups, a urethane acrylate oligomer of a bifunctional group, at least one photocurable monomer and a photoinitiator. The photocurable monomer according to claim 1, wherein the photocurable monomer is acrylic morpholine (ACMO), tetrahydrofurfuryl acrylate (THFA), hydroxy ethyl acrylate (HEA), hydroxy propyl acrylate (HPA), isobornyl acrylate ( IBOA), trimethylolpropane triacrylate, ethoxylated (3 moles) trimethylolpropane triacrylate, ethoxylated (6 moles) trimethylolpropane triacrylate, propoxylated (3 moles) trimethylol UV curable coating composition, characterized in that it is selected from the group consisting of propane triacrylate (TMPTA) and pentaerythritol triacrylate (PETA). The UV curable coating composition of claim 1, further comprising a slip agent. 4. The UV curable coating composition of claim 3, wherein the slip agent is selected from the group consisting of phosphate acrylates, polyether siloxane compounds, and fluoroalkyl compounds. According to claim 1, 20 to 50 parts by weight of a polyester acrylate oligomer of at least 6 functional groups, 5 to 30 parts by weight of a urethane acrylate oligomer of a bifunctional group, 20 to 40 parts by weight of at least one photocurable monomer and a photoinitiator UV curable coating composition comprising 5 to 20 parts by weight. The UV curable coating composition of claim 3, wherein the slip agent is included in an amount of 0.1 to 1 parts by weight. A steel sheet comprising a coating layer cured by applying UV curable coating composition of any one of claims 1 to 6 on a steel sheet.