KR20160096571A - Thermosetting bisphenol F-type epoxy powder coating composition with excellent corrosion resistance and eco friendliness and a pipe coated with the composition - Google Patents

Abstract

The present invention relates to a thermosetting bisphenol F-type epoxy powder paint composition and a pipe coated with the composition. More specifically, the present invention relates to a low-viscosity thermosetting bisphenol F-type epoxy powder paint composition and a pipe coated with the composition. According to the present invention, the composition contains a bisphenol F-type epoxy resin, an amine-based hardening agent, a hardening accelerator, a pigment, and a filler, while not containing a bisphenol A-type epoxy resin which is environmentally harmful. In addition, the composition of the present invention exhibits excellent properties including flowability, adhesiveness, chemical resistance, bendability, corrosion resistance, and eco-friendliness, thereby being applicable for coating an interior/exterior of pipes.

Description

TECHNICAL FIELD [0001] The present invention relates to a thermosetting bisphenol F type epoxy powder coating composition excellent in corrosion resistance and environmental friendliness and a pipe coated with the composition.

The present invention relates to a thermosetting bisphenol F type epoxy powder coating composition and a pipe coated with the composition, and more particularly to a pipe coated with a bisphenol F type epoxy resin, an amine type curing agent, a curing accelerator, a pigment and a filler, Which is excellent in flow, adhesion, chemical resistance, bendability, corrosion resistance and environmental friendliness, and is suitable for internal / external coating of pipe. Thermosetting bisphenol F type An epoxy powder coating composition and a pipe coated with the composition.

Powder coatings are mainly applied to pipes, and they are divided into two types, namely, external use and internal use. Powder coating systems include single layer coating method, multi-layer coating method, and three-layer coating method depending on coating method and application, and single layer melt adhesion method is mainly used for pipe coating.

The thermosetting epoxy powder coating applied to the outside of the pipe is to protect the pipe from external heat and pressure. In order to transfer the contents of 90 ° C or less, a coating film having a glass transition temperature of 100 ° C or more should be formed in a single coating, The back pipe material and adhesion should be excellent.

In recent years, coal tar, cement lining, or liquid epoxy coating has been applied as a thermosetting epoxy powder coating on the inside of a pipe. In recent years, the application of epoxy powder coating has been expanded and its market is also increasing.

The primary purpose of the pipe coating is to improve the adhesion between the pipe substrate and the powder coating as described above and to prevent corrosion of the pipe by causing the coating to peel off or not to be swollen by pipe contaminants or by external contaminants have. In addition, additional functions are required for the in-pipe painting in that the paint surface always contacts the dynamic conveyance within the pipe. One of them is an excellent smoothness for efficient transport of the material to be conveyed, so that the liquid passing through the inside of the pipe can be transported while minimizing the friction with the pipe, and the other is chemical resistant, This is to minimize the chemical reaction with the chemical substances generated according to the environment of the substance.

Conventional epoxy resin powder coatings mainly include a thermosetting epoxy resin containing a part of a bisphenol A type epoxy resin, a urethane substituted or novolak-modified epoxy resin, and a high molecular weight polyhydric phenol curing agent, dicyandiamide Based auxiliary curing agent and an acid anhydride are included as a curing agent, and additives are included. Particularly, powder coatings applied to pipes have been mainly applied to bisphenol A type epoxy resin, and these paints have a high viscosity, and their mechanical properties and corrosion resistance are superior to those of other paints.

However, bisphenol A is a kind of environmental hormone, and environmental hazard and human body controversy are constantly being raised. Recently, stability problem of bisphenol A type epoxy resin has been emerged especially in drinking water pipes. That is, although there is a low possibility that bisphenol A is eluted into tap water supplied at room temperature, there is a concern that long-term exposure to low-concentration bisphenol A may be dangerous.

As a result, a bisphenol F type epoxy powder coating material which can achieve the same level of adhesion and corrosion resistance as the bisphenol A type epoxy resin powder coating material and which can not detect environmental harmful components has been developed. For example, Korean Patent No. 10-0904279 discloses a bisphenol F type epoxy resin having an epoxy equivalent of 600 to 2000 g / eq, a bisphenol F type epoxy resin having an epoxy equivalent of 200 to 550 g / eq and an epoxy equivalent of 30 to 700 g / A powder coating material containing a curing agent is disclosed. However, these powder coatings have poor mechanical properties such as bending properties, and the use of an epoxy hardener may deteriorate the water resistance such as long-term high-temperature corrosion resistance and durability, and the glass transition temperature may be lowered.

Therefore, it is an object of the present invention to provide a bisphenol F epoxy resin coating composition which is excellent in long-time high-temperature properties such as flexibility, mechanical properties such as flexibility, long-term high temperature corrosion resistance, Development is required.

The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method for producing a water- And is excellent in flowability, flexibility, smoothness and the like, and is particularly suitable for pipe coating, and a pipe coated with the composition.

In order to solve the above-mentioned technical problem, the present invention provides a curable resin composition comprising 40 to 80% by weight of a bisphenol F type epoxy resin, 0.1 to 5% by weight of an amine-based latent curing agent, 0.1 to 5% by weight of a curing accelerator, 1 to 10% by weight of a filler and 20 to 40% by weight of a filler.

According to another aspect of the present invention, there is provided a pipe coated with the thermosetting powder coating composition.

The powder coating composition of the present invention can provide a thermosetting coating film excellent in flowability, flexibility, smoothness, adhesion, chemical resistance, wetness, water resistance, corrosion resistance, chemical resistance, bendability and corrosion resistance, It is very suitable for internal / external painting.

Hereinafter, the present invention will be described in detail.

The epoxy equivalent of the bisphenol F type epoxy resin contained in the powder coating composition of the present invention is preferably 600 to 1300, more preferably 800 to 1200. When the epoxy equivalent of the bisphenol F epoxy resin is less than 600, the viscosity of the powder coating is low and the adhesion to the substrate is improved. However, the flexibility is poor and the storage stability of the coating is deteriorated. The adhesion to the substrate is deteriorated, and therefore, the water resistance and corrosion resistance may be deteriorated.

The content of the bisphenol F type epoxy resin in the composition of the present invention is preferably 40 to 80% by weight, more preferably 55 to 70% by weight, and more preferably 60 to 70% by weight based on 100% by weight of the composition . When the bisphenol F type epoxy resin content is less than 40% by weight, the flexibility is lowered. When the bisphenol F type epoxy resin content is more than 70% by weight, the flexibility of the powder coating composition is increased, but the heat resistance and chemical resistance can not be expected due to an increase in the organic content in the cured coating film.

The bisphenol F type epoxy resin is a part where epoxy groups on both sides of the resin and hydroxyl groups in the resin participate in the reaction, and properties of the coating film may be significantly changed depending on the kind of the curing agent used.

The powder coating composition of the present invention can improve physical properties such as high temperature corrosion resistance, chemical resistance and adhesion property by curing a bisphenol F type epoxy resin using an amine-based latent curing agent as a curing agent. The amine-based latent curing agent usable in the present invention preferably has an active hydrogen equivalent of 10 to 50, and more specifically, it is preferable to use a dicyandiamide-based curing agent.

The content of the amine-based latent curing agent in the composition of the present invention is 0.1 to 5 wt%, preferably 0.1 to 2 wt%, more preferably 0.5 to 1.5 wt%, based on 100 wt% of the composition. When the content of the amine-based latent curing agent is less than 0.1% by weight, the curing of the resin becomes insufficient. When the content of the amine-based latent curing agent is more than 5% by weight, unreacted amine and moisture may react with each other to cause discoloration of the coating film and serious blistering.

As the curing accelerator used in the powder coating composition of the present invention, known curing accelerators can be used without any particular limitation. Examples of the curing accelerator that can be used include quaternary ammonium such as triphenylphosphine, benzyltriphenylphosphonium chloride, butyltriphenylphosphonium chloride and tetraphenylphosphonium chloride; Dimethylimidazole, 1,5-dimethylimidazole, 2-butyl-5-chloro-1H-imidazole-4-carboaldehyde, 2-methylimidazole, Vinylimidazole, climbazole, 1,1-carbonyldiimidazole, tert-butyldimethylsilyl chloride, 2-ethyl-4-methylimidazole, 2-phenylimidazole, Imidazoles such as 1-benzyl-2-methylimidazole, 2-butylimidazole; And mixtures thereof. However, the present invention is not limited thereto.

The content of the curing accelerator in the composition of the present invention is 0.1 to 5 wt%, preferably 0.1 to 1 wt%, more preferably 0.1 to 0.5 wt%, based on 100 wt% of the composition. When the content of the curing accelerator is less than 0.1% by weight, the curing of the resin becomes insufficient. When the content of the curing accelerator exceeds 5% by weight, the curing is excessively accelerated. When the content of the curing accelerator is out of the above range, And stability of physical properties of the coating film are lowered.

As the pigment to be used in the powder coating composition of the present invention, there is no particular limitation on its kind, and known pigments commonly used for coloring in the production of powder coatings can be used. Examples of usable pigments include, but are not limited to, those selected from the group consisting of titanium dioxide, ultramarine blue, phthalocyanine blue, phthalocyanine green, carbon black, and mixtures thereof.

The content of the pigment in the composition of the present invention is preferably 1 to 10% by weight, more preferably 1 to 5% by weight, and more preferably 2 to 5% by weight based on 100% by weight of the composition. If the content of the pigment is less than 1% by weight, the coating ability of the coated film can not be sufficiently secured. If the content exceeds 10% by weight, mechanical properties and dispersibility are deteriorated.

As the filler to be used in the powder coating composition of the present invention, known fillers can be used without any particular limitation. Examples of usable fillers include, but are not limited to, those selected from the group consisting of barium sulfate, calcium carbonate, silica, alumina hydroxide, mica, wollastonite, talc, zinc and mixtures thereof.

The content of the filler in the composition of the present invention is 10 to 40% by weight, preferably 15 to 35% by weight, and more preferably 20 to 30% by weight based on 100% by weight of the composition. If the content of the filler is less than 10% by weight, the hiding power of the coating film is deteriorated, and if it exceeds 40% by weight, problems may occur in the appearance of the coating film.

The powder coating composition of the present invention may further contain usual additives in addition to the above-mentioned components, depending on the intended use and environment of the powder coating. For example, as an additive for enhancing the appearance of paints, an acrylic flowability improver (for example, PPV-5, PPV 88: manufactured by Estron Co., Ltd., Arctern 4F: manufactured by BASF Corp.) , A silicone fluidity improver (e.g., PEEL-200 manufactured by ESTRON Co., Ltd.) may be contained in an amount of 1 to 1.5 wt% based on 100 wt% of the composition, respectively have. Also, as a pinhole inhibitor used in ordinary powder coating materials, 2-hydroxy-1,2-dipentanone (e.g., 2-hydroxy-1,2-dipentanone) which contributes to the prevention of gelation and delayed release of bubbles generated during the reaction For example, benzoin: manufactured by DMS Co.) in an amount of 0.1 to 1.5% by weight based on 100% by weight of the composition. In addition to the above additives, an amide-based, polypropylene-based, olefin-based, and / or a teflon-based wax and / or a dispersing agent may be further added to the powder coating composition. Propylene-based wax and hydrophilic or hydrophobic silica may further be contained in usual amounts.

There is no particular limitation on the method for producing the powder coating composition of the present invention, and the powder coating composition can be produced using a conventional method and apparatus for producing powder coatings known in the art. According to one embodiment of the present invention, the powder coating composition of the present invention can be prepared by the following procedure, but is not limited thereto.

In the first step, raw materials such as epoxy resin, curing agent, curing accelerator, pigments and additives are uniformly mixed and then preliminarily dry-mixed at about 2,000 to 5,000 rpm for about 100 to 600 seconds using a Henschel mixer, A pre-mixing process is carried out to maintain a physical property.

In the two-step process, the preliminarily dispersed raw materials are subjected to melt mixing and dispersion at a temperature of 90 to 120 ° C using a dispersing machine (e.g., PLK46, Booth Company) through the one-step process. The molten and mixed raw material is passed through a cooling roll and a cooling belt to produce a chip having a size of 50 to 100 mm and a thickness of 1 to 5 mm.

In the three-step process, the chip produced through the two-step process is pulverized to have a uniform powder particle size (average particle size of 40 to 60 mu m) mechanically using a pulverizer (e.g., Hammer mill, A- . The particle size of the powder is very closely related to the workability of the powder coating, and the particle size is adjusted so that the average particle size is preferably 15 to 45 microns and the particle size of 250 microns or more is present within 0.3 weight%.

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

Examples and Comparative Examples

Each component was blended in the blend ratio (% by weight) shown in Table 1 below to prepare a thermosetting powder coating for pipes.

Epoxy resin 1: Bisphenol F type, epoxy equivalent 1100 ~ 1200 (Kukdo Chemical)

Epoxy resin 2: Bisphenol F type, epoxy equivalent 900 to 1000 (Kukdo Chemical)

Epoxy resin 3: Bisphenol A type, epoxy equivalent 1100 to 1200 (KCC)

Epoxy resin 4: bisphenol A type, epoxy equivalent 900 to 1000 (KCC)

Phenol Hardener 1: Bisphenol F phenolic Hardener (Kukdo Chemical)

Phenol hardener 2: bisphenol A phenolic hardener (KCC)

Amine curing agent 1: amine-based latent curing agent, DICY (Air Product)

Amine curing agent 2: amine-based latent curing agent, DMPF (THOMAS SWAN)

Curing accelerator: 2-MI (SINKOKU)

Additives: Surface conditioner, PLP-100 (KS Chemical)

TiO ₂ : CR-80 (ISHIHARA)

Colored pigment: MA-100 (MITSUBISHI)

Filler 1: NB-0070 (Korea Semiconductor Material)

Filler 2: OMYCARB 5 (Korea OMYA)

Filler 3: HANSIL C-15J (Korea Semiconductor Material)

The powder coatings prepared in the Examples and Comparative Examples were subjected to a physical property evaluation test in the following manner. The results are shown in Table 2 below.

[Property evaluation method]

The following properties evaluation methods were carried out according to Canadian Standard for Pipe (CSA Z245.20.10) and National Standard (KS D 4317).

Flexibility

When a specimen coated with steel of 25 mm (width) x 250 mm (length) x 6 mm (thickness) was prepared as a flexural test specimen and the specimen was folded using a mandrel at an angle of 3 ° at room temperature, It was observed whether or not it was broken.

Impact

The specimen coated on steel with a thickness of 25 mm (width) x 250 mm (length) x 6 mm (thickness) was made to have a temperature of -30 ° C, and then an impact of about 1.5 J was applied to observe the fracture.

Cathodic separation

A specimen coated on steel of 100 mm (width) x 100 mm (length) x 6 mm (thickness) was prepared, a 3 mm diameter hole was drilled in the center of the specimen and a 3.5 inch diameter cylinder was sealed on the specimen . Then, the cylinder was filled with NaCl solution, and the platinum wire was immersed therein. Then, the substrate and the cylinder were placed in an oven at 65 ° C. and a voltage of 1.5 V was applied to the platinum wire and the test substrate for 48 hours and 7 days to measure the peeling distance from the hole. The larger the peeling distance, the lower the adhesion of the powder coating composition to the substrate.

Abdominal aquatic

The specimens coated on steel of 100 mm (width) x 100 mm (length) x 6 mm (thickness) were thoroughly immersed in a thermostatic chamber containing 75 ° C water. After 24 hours and 7 days, ) Ⅹ30㎜ (lengthwise), and the corrosion resistance was tested by peeling off the depth line to the base. The corrosion resistance evaluation grade is classified into rating 5 (R5) from rating 1 (R1) according to the release area, and the larger the number, the broader the release area (that is, the poor weatherability is poor).

As can be seen from the above Table 2, the bisphenol F epoxy powder coating composition for pipes excellent in corrosion resistance according to the present invention exhibited excellent physical properties both in high-temperature long-term boiling water adhesion, corrosion resistance and bending property, And also showed excellent physical properties in the test. In addition, it does not contain a bisphenol A type epoxy resin and is environmentally friendly and safe.

Claims (8)

Based on 100% by weight of the composition,
60 to 70% by weight of a bisphenol F type epoxy resin;
0.1 to 1.5% by weight of an amine-based latent curing agent;
0.1 to 1% by weight of a curing accelerator;
1 to 5% by weight of pigment; And
15 to 35% by weight of a filler selected from barium sulfate, calcium carbonate, silica and mixtures thereof,
A resin composition containing no bisphenol A type epoxy resin,
Thermosetting powder coating composition. The thermosetting powder coating composition according to claim 1, wherein the bisphenol F type epoxy resin has an epoxy equivalent of 600 to 1300. The thermosetting powder coating composition according to claim 1, wherein the amine-based latent curing agent has an active hydrogen equivalent of 10 to 50. The method of claim 1, wherein the curing accelerator is selected from the group consisting of triphenylphosphine, benzyltriphenylphosphonium chloride, butyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, 1-methylimidazole, 2-methylimidazole, Dimethylimidazole, 1,5-dimethylimidazole, 2-butyl-5-chloro-1H-imidazole-4-carboaldehyde, vinylimidazole, climbazole, 2-ethylimidazole, 2-ethylimidazole, 1-benzyl-2-methylimidazole, 2-butyldimethylsilyl chloride, And mixtures thereof. ≪ RTI ID = 0.0 > 11. < / RTI > The thermosetting powder coating composition according to claim 1, wherein the pigment is selected from the group consisting of titanium dioxide, ultramarine blue, phthalocyanine blue, phthalocyanine green, carbon black, and mixtures thereof. A pipe coated with the thermosetting powder coating composition of any one of claims 1 to 5. The pipe according to claim 6, wherein the inside of the pipe is coated with the thermosetting powder coating composition. The pipe according to claim 6, wherein the pipe is coated with the thermosetting powder coating composition.