KR101965528B1 - Powder coating composition having excellent chipping resistance and alloys comprising a cured coating layer formed from the same - Google Patents

Abstract

The present invention relates to an alloy containing a powder coating composition and a cured coating layer formed therefrom, which can secure an improved resistance to chipping, corrosion resistance, adhesion, workability and durability by applying a one-coating system.

Description

TECHNICAL FIELD [0001] The present invention relates to a powder coating composition excellent in chipping resistance and an alloy including a cured coating layer formed therefrom. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to an alloy containing a powder coating composition excellent in chipping resistance and a cured coating layer formed therefrom.

As a coil spring dual (DUAL) paint, an epoxy resin, a plate-like filler and zinc are introduced in the case of undercoating, and an epoxy is used in the case of a topcoat, as described in Patent International Patent Publication No. WO 2011/012627 A2. Resin, elastomer-modified bisphenol A epoxy resin, and a foaming agent to form a foam in the film to withstand external impacts.

According to the prior art, there is a concept of foaming capable of absorbing external impact on the upper surface, but it has a disadvantage in that the strength of the coating itself decreases due to formation of many pores in the coating, Since the painting process is carried out with the system, it is necessary to invest in facilities and it is troublesome to manage two separate painting booths.

It is an object of the present invention to provide an alloy containing a powder coating composition and a cured coating layer formed therefrom, which can secure an improved resistance to chipping, corrosion resistance, adhesion, workability and durability by applying a one-coating system .

The powder coating composition of the present invention comprises 10 to 60% by weight of a bisphenol A type epoxy resin, 10 to 40% by weight of an epoxy reinforcing agent, 1 to 10% by weight of a phenol novolac epoxy resin, 10 to 30% by weight of a filler 10 to 20% by weight of a hardener, and 1 to 10% by weight of a zinc powder.

The alloy of the present invention comprises a cured coating layer formed of the powder coating composition.

Since the powder coating composition of the present invention can form a coating film by applying a one-coat coating method, workability can be improved and strength against intrinsic coating film foam type by ensuring the chipping resistance, corrosion resistance, adhesion property, durability, And it can be applied to a coil spring for an automobile.

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

The powder coating composition of the present invention comprises 10 to 60% by weight of a bisphenol A type epoxy resin, 10 to 40% by weight of an epoxy reinforcing agent, 1 to 10% by weight of a phenol novolac epoxy resin, 10 to 30% by weight of a filler 10 to 20% by weight of a hardener, and 1 to 10% by weight of a zinc powder.

The bisphenol A type epoxy resin may have a linear structure in order to secure mechanical properties, and an epoxy equivalent of 1,000 to 1,500 g / eq may be used. When the equivalent weight is less than 1000 g / eq, the flexibility decreases and the storage stability of the coating decreases. When the equivalent weight exceeds 1500 g / eq, the wettability is lowered due to an increase in the viscosity of the coating due to an increase in the resin viscosity, Which is undesirable. The thermosetting bisphenol A type epoxy resin can be synthesized directly according to a known method, or a commercially available material can be used.

The composition of the present invention may contain 10 to 60% by weight of a bisphenol A type epoxy resin with respect to 100% by weight of the total composition. When the content of the bisphenol A type epoxy resin is out of the above range, it is not preferable because the corrosion resistance, chemical resistance and adhesion are poor.

The composition of the present invention comprises an epoxy reinforcing agent (Toughening Agent). Epoxy resins have the drawback of being susceptible to transient impacts because they have brittleness due to high crosslinking density. In the present invention, the embrittlement of the epoxy resin can be improved by mixing and hardening the epoxy resin with a reinforcing agent in order to improve the vulnerability. This is because the added reinforcing agent forms a fine dispersed phase in the matrix resin to absorb the impact externally applied, thereby increasing the formulation viscosity, toughness (resistance to crack propagation) without affecting the modulus and Tg, Can be significantly improved.

The epoxy reinforcing agent may be an amphiphilic hydroxyl group-containing block copolymer or a mixture containing it. The amphiphilic block copolymer containing at least one hydrophilic block and at least one hydrophobic block selected from the group consisting of polyethylene oxide, polyethylene-polypropylene copolymer, polymethyl methacrylate, and polyacrylamide, And the hydrophobic block may be at least one selected from the group consisting of polybutylene oxide, polyhexylene oxide, polydodecylene oxide, and polyacrylamide, or a combination thereof.

The epoxy strengthening agent may be one having an epoxy equivalent of 800 to 1,200 g / eq, and an appropriate ratio should be included because there is a difference in hardness of the coating depending on the range.

The first composition may comprise from 10 to 30% by weight of an epoxy reinforcement, based on 100% by weight of the composition. Outside of the above range, flowability and chipping property become poor, which is not preferable.

The composition of the present invention may comprise from 10 to 40% by weight of an epoxy reinforcement based on 100% by weight of the composition. Outside of the above range, flowability and chipping property become poor, which is not preferable.

The present invention includes a phenol novolac epoxy resin to improve corrosion resistance and adhesion. The phenol novolak epoxy resin preferably has an equivalent weight of 600 to 1,000 g / eq, more preferably 700 to 900 g / eq. When the equivalent weight is less than 600 g / eq, there is a problem that storage stability is poor and blocking occurs. When the equivalent weight is more than 1,000 g / eq, there is a problem that the curability required by the present invention can not be obtained.

The composition of the present invention may comprise 1 to 10% by weight of phenol novolac epoxy resin relative to 100% by weight of the total composition. If the content of the phenol novolak epoxy resin is out of the above range, the corrosion resistance and adhesion may be poor.

The filler included in the composition of the present invention plays a role in improving mechanical properties and is used for improving mechanical properties such as feldspar, barium sulfate, silica, alumina hydroxide, titanium oxide, calcium carbonate, magnesium carbonate, alumina, mica, wollastonite, And a combination thereof.

The composition of the present invention may contain 10 to 30% by weight of a filler based on 100% by weight of the total composition. When the content of the filler is too low, the mechanical properties are poor, and when the content is too high, the properties such as flex resistance tend to deteriorate.

The curing agent contained in the composition of the present invention may be a phenol curing agent such as a bisphenol A phenolic curing agent. It is possible to cure at lower temperature than amine curing agent by application of phenol curing agent, and it also helps impart flexibility of coating film. The hydroxyl group equivalent of the phenolic curing agent is preferably 200 to 300 g / eq. When the equivalent weight is less than 200 g / eq, the physical properties of the coating film become too hard and the bending property decreases. When the equivalent weight exceeds 300 g / eq, the coating film becomes too soft and the bending property becomes good.

The composition of the present invention may contain 10 to 20% by weight of a curing agent based on 100% by weight of the total composition. When the content of the curing agent is too low, the strength of the coating film is lowered due to the decrease of the crosslinking density, whereas when the content is more than 20% by weight, the crosslinking density of the coating film is abruptly generated, not.

The zinc powder contained in the composition of the present invention further enhances the corrosion resistance. The composition of the present invention may comprise 1 to 10% by weight of zinc powder relative to 100% by weight of the total composition. If the content of the zinc powder is too low, the corrosion resistance becomes poor. If the zinc powder content is too high, the specific gravity of the paint increases, which may affect the workability.

The composition of the present invention can further improve the workability in the preheating coating by further including the ruggedness additive. Examples of the roughening additive include R-972 available from EVONIK, and BENTONE 38 available from ELEMENTIS SPECIALTIES.

The composition of the present invention may comprise from 0.1 to 5% by weight of the roughening additive relative to 100% by weight of the total composition. If the content of the plasticizing additive is out of the above range, the appearance and workability of the paint are poor, which is not preferable.

The composition of the present invention may include at least one additive selected from a curing accelerator, a surface modifier, an antifoaming agent, and an amide wax. The additive may be added in an amount of 1 to 5% by weight. If the content of the additive is less than 1% by weight, the effect of adding the additive can not be obtained. If the additive is more than 5% by weight, the overall physical properties of the powder coating material may be deteriorated.

According to another aspect of the present invention, there is provided an alloy comprising a cured coating layer formed from the powder coating composition. The alloy may be applied to various articles such as automobile parts such as spring coils for automobile parts.

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

[Example]

The powder coating compositions were prepared as shown in Table 1, and the physical properties thereof were evaluated.

Epoxy resin 1: Bisphenol A type epoxy equivalent 1100 to 1200 g / eq (KCC, KD-214K National highway, KER 7034 Kumho P & B)

Epoxy resin 2: Bisphenol A epoxy equivalent 780 to 840 g / eq (KCC)

Epoxy resin 3: Epoxy reinforcing agent (Toughening) Epoxy equivalent 950 to 1100 g / eq, viscosity 4500

Epoxy resin 4: phenol novolak epoxy equivalent 750 to 850 g / eq (DER 672U, DOW)

Phenol curing agent: bisphenol A type phenolic curing agent OH equivalent 230 to 280 g / eq (KCC)

Amine curing agent: amine-based curing agent, DICY (1400F AIR products)

Curing accelerator: 2MI curing accelerator (KCC)

Rickling Additive 1: R-972 (EVONIK)

Additive 2: BENTONE 38 (ELEMENTIS SPECIALTIES)

Filler 1: Calcium carbonate (OM-1, Omia)

Filler 2: Feldspar (MF-200, BMS)

Zinc powder: ZINC DUST # 330 SP

Property evaluation method

(1) Appearance

The specimens were painted on a 75 mm * 150 mm * 0.7 mm CR steel plate for appearance evaluation, and visually confirmed the appearance of the specimens. The pinholes, cratering, and glittering were measured.

(2) Flowability

A 16 mm diameter coil spring was preheated in a hot air oven at 125 DEG C for 40 to 60 minutes, then coated with a coating thickness of 400 mu m or more, cured at 180 DEG C for 40 minutes, and then visually evaluated for flowability.

(3) Adhesiveness

The specimens prepared in the same manner as in the above appearance evaluation were peeled off by peeling the tape by 10 chambers at intervals of 1 mm in accordance with ISO 2409.

(4) Impact resistance

Prepare specimens coated on 75mm * 150mm * 0.7mm CR steel sheet for impact evaluation, then drop 1kg of weight from 50cm height using Dupont impact tester and check whether the coating is cracked.

(5) Corrosion resistance

The test specimens prepared in the same manner as in the above appearance evaluation were subjected to a salt spray test ASTMB 117 for 4 hours, a drying condition of 60 ° C for 1 hour, a wet condition of 60 ° C, 95% RH for 2.5 hours A total of 7.5 hours is defined as 1 cycle and 2 cycles are defined as 1 cycle. After each cycle test, tape-peel off the cross-cut part of 2 mm and record the degree of peeling.

(6) Chipping property

The specimens prepared in the same manner as in the above appearance evaluation were subjected to chipping evaluation according to GM14700 test, and after 480 hours under the salt spray ASTM B117 condition, it was confirmed whether or not rust occurred.

Claims (8)

10 to 60% by weight of a bisphenol A type epoxy resin, 10 to 40% by weight of an epoxy reinforcing agent, 1 to 10% by weight of a phenol novolak epoxy resin, 10 to 30% by weight of a filler, 10 to 20% And 1 to 10 wt% zinc powder,
Wherein the epoxy enhancer is an amphiphilic hydroxyl group-containing block copolymer,
Wherein the amphiphilic hydroxyl group-containing block copolymer comprises a hydrophilic block and a hydrophobic block,
Wherein the hydrophilic block is at least one selected from the group consisting of polyethylene oxide, polyethylene-propylene copolymer and polymethyl methacrylate,
Wherein the hydrophobic block is at least one selected from polybutylene oxide, polyhexylene oxide or polydodecylene oxide,
Wherein the amphiphilic hydroxyl group-containing block copolymer is an epoxy resin having an epoxy equivalent of 800 to 1,200 g / eq. The powder coating composition according to claim 1, wherein the bisphenol A epoxy resin has an epoxy equivalent of 1,000 to 1,500 g / eq. delete The powder coating composition according to claim 1, wherein the phenol novolak epoxy resin has an epoxy equivalent of 600 to 1,000 g / eq. The powder coating composition according to claim 1, wherein the curing agent is a phenol curing agent having a hydroxyl equivalent of 200 to 300 g / eq. The powder coating composition of claim 1, further comprising a roughening additive. An alloy comprising a cured coating layer formed from the powder coating composition according to any one of claims 1, 2 and 4 to 6. 8. The alloy according to claim 7, which is a coil spring for an automobile.