KR20120077167A - Epoxy semi-matt powder coatings for engine block, manufacturing method thereof and coating method - Google Patents

Abstract

PURPOSE: An epoxy semi-matt powder coating is provided to have excellent adhesion with an object, and to have excellent salt water resistance, and chemical resistance, and not to generate a volatile organic compound in manufacturing, painting, and drying process of paint. CONSTITUTION: An epoxy semi-matt powder coating for engine block comprises 20-80 parts by weight of an epoxy resin of which epoxy equivalent is 500-2000 g/eq, 1-10 parts by weight of a first epoxy hardener of which epoxy equivalent is 50-200 g/eq, 0.5-10 parts by weight of a second epoxy hardener of which epoxy equivalent is 20-100 g/eq, 1-10 parts by weight of a special curing agent of which epoxy equivalent is 200-500 g/eq, 0.1-2 parts by weight of a curing accelerator, 5-60 parts by weight of inorganic filler, and 0.1-15 parts by weight of additives based on total weight of the epoxy semi-matt powder coating for engine block.

Description

Epoxy semi-matte powder coating composition for engine block, manufacturing method and coating method

The present invention relates to an epoxy semi-glow powder coating composition, a manufacturing method and a coating method thereof, which are coated on an engine cylinder block made of cast iron castings or aluminum castings, and more particularly, bisphenol A (BPA) and epichlorohex. Epoxy semi-glow for engine block that can form strong coating film without environmental damage by coating epoxy block with epoxy resin produced by synthesizing epichlorohydrin (ECH) and epoxy curing agent. The present invention relates to a powder coating composition, a manufacturing method thereof, and a coating method.

In general, engine cylinder blocks made of cast iron castings, aluminum castings, etc. are used as corrosion preventing and protective coating agents, and liquid enamel paints and liquid urethane paints have already been widely applied. The coating film cured by coating such a liquid coating on the coating material (engine block) is weak in adhesion and impact resistance to the coating material, not only the hardness of the coating film but also a satisfactory level of corrosion resistance.

In addition, the engine block coated with a liquid paint is not good workability, such as chipping (chipping) during cutting, processing. In addition, the liquid paint is a paint containing VOC (volatile organic compound), which is harmful to the human body and the environment. It was developed to improve this problem is the epoxy semi-glow powder coating for the engine block, and the difference from the liquid paint is widely used at present. In addition, the epoxy semi-glow powder coating for the engine block coating has the following characteristics when compared with the conventional epoxy powder coating for steel coating.

First, this paint is a powder coating developed so that almost no bubbles are generated even when the casting containing many pores is applied.

Secondly, this paint is a fast-curing powder coating developed for the characteristic of applying a thick coating on the coating process to form a cured coating in a short time.

Thirdly, this paint is used for cutting and processing of the finished engine block, so that the chipping property is closely related to workability and productivity, so that the curing speed, viscosity, glass transition temperature (Tg) of the coating film, fluid additives, etc. This is a specially designed powder coating.

Fourth, this paint is produced through a dispersion process and a grinding process different from the general powder coating in the manufacturing process.

Epoxy semi-glow powder coating for engine block is a powder coating made by mixing, melting, dispersing, pulverizing and filtering colored pigments, sieving pigments and other additives based on epoxy resins and two or more different epoxy curing agents and curing accelerators. Epoxy semi-glow powder coating for engine block coating is epoxy type powder coating with epoxy resin as a main component.

[Epoxy Manufacturing Method and Reaction of Epoxy and Curing Agent]

BPA resin, which is most commonly used in epoxy powder coating, is the most important commercially used epoxy resin to date for condensation reaction between diphenylopropane (DPP) and epichlorohydrin (ECH), known as BPA. It is a diglycidyl ether type epoxy resin produced by. There are direct and indirect methods, and NaOH is used as a catalyst. Depending on the properties, there are dilution type with liquid, semi-solid, solid and reactive diluent and solvent type with solvent.

In general, BPA epoxy resins have a benzene nucleus (bisphenol A), which makes it difficult to rotate freely, which improves chemical resistance, adhesion, toughness, and high temperature characteristics.

Epoxy powder coating is made by the reaction of epoxy resin and epoxy curing agent. Examples of epoxy curing agents generally used are dicyandiamide (DICY) and its derivatives, amine derivatives, carboxylic acid (Carboxylic acid, Carboxyl-Terminated Polyester Resins, etc.), imidazole.

(Imidazole) and Phenolic Hydroxyl Terminated Curing Agents containing phenolic hydroxyl groups at the terminals.

The reaction formula of epoxy and dicyandiamide is as follows.

The reaction scheme between epoxy and amine is as follows.

The reaction formula between the epoxy and the polyster resin containing a carboxyl group at the terminal is as follows.

The reaction of epoxy and imidazole is as follows.

The reaction scheme between the epoxy and the curing agent containing a phenolic hydroxy group at the terminal is as follows.

The painting of the engine block is different from that of general steel, and the specially designed design has to be made because the required level of physical properties of the paint is different.

Engine blocks coated with liquid paint have problems in mechanical and chemical properties of the coating film, and liquid paint has various problems in terms of safety as well as environmental damage due to VOC generation. In addition, the engine block coated with other powder coating is difficult to be completely cured in the designated drying furnace because the thickness of the engine block is thick, there is a problem of bubbles in the appearance of the coating film, and has many problems in terms of physical properties of the coating film.

Therefore, there is a need for an epoxy semi-glow powder coating composition for engine block coating using a specific epoxy resin, an epoxy curing agent, a special catalyst, and a special additive.

In addition, by painting the engine block with an epoxy semi-glow powder coating, there is no abnormality in mechanical and chemical properties and does not emit harmful substances to the human body. Necessity arises.

The present invention was created by the above needs, and an object of the present invention is to provide an epoxy semi-glow powder composition for the engine block coating by providing an epoxy semi-glow powder coating composition using a specific epoxy resin, an epoxy curing agent, a special catalyst, and a special additive. Epoxy semi-glow powder coating composition for engine block coating, its manufacturing method and coating method that have no abnormality in mechanical and chemical properties and do not emit harmful substances to human body when painting with paint, and also have environmentally safe properties. It is.

The object of the present invention as described above is 20 to 80 parts by weight of an epoxy equivalent of 500 to 2000 g / eq epoxy resin relative to the total weight of the epoxy semi-glow powder coating composition for the engine block; 1 to 10 parts by weight of the first epoxy curing agent having an epoxy equivalent of 50 to 200 g / eq; 0.5 to 10 parts by weight of a second epoxy curing agent having an epoxy equivalent of 20 to 100 g / eq; 1 to 10 parts by weight of a special curing agent having an epoxy equivalent of 200 to 500 g / eq; 0.1 to 2 parts by weight of a curing accelerator; 5 to 60 parts by weight of inorganic filler; And 0.1 to 15 parts by weight of additives; it can be achieved by providing an epoxy semi-glow powder coating composition for the engine block comprising a.

In addition, the first epoxy curing agent and the second epoxy curing agent may be at least any one selected from the group consisting of an acrylic resin (Carboxylic functional acrylic resin) curing agent having a carboxyl functional group.

The curing accelerator may be any one selected from the group consisting of imidazole compounds, amine compounds, and mixtures thereof.

In addition, the inorganic filler may be any one selected from the group consisting of barium sulfate, calcium carbonate, silica, titanium dioxide, magnesium hydroxide, alumina hydroxide, cray, mica, alumina, wollastonite, talc and mixtures thereof. have.

In addition, the pigment may be characterized in that any one selected from the group consisting of bismuth vanadate, cyanine green, cyanine blue, iron oxide, iron oxide, carbon black, Naver blue and mixtures thereof.

In addition, the epoxy semi-glow powder coating composition for an engine block, 0.1 to 15 parts by weight of an additive; may be characterized in that it further comprises.

In addition, the epoxy semi-glow powder coating composition for an engine block may be characterized by further comprising an epoxy resin having an epoxy equivalent of more than 2000 g / eq and less than 3000 g / eq.

In addition, the epoxy semi-glow powder coating composition for an engine block is a 1: 1 to 9: 1 epoxy resin having an equivalent weight of 500 g / eq or more and 2000 g / eq or less and an epoxy resin having an equivalent weight of more than 2000 g / eq and 3000 g / eq or less. It may be characterized by including in the ratio of.

On the other hand, an object of the present invention as another category, the step of weighing the constituent material of the epoxy semi-glow powder coating composition for the engine block (S110); B step S120 of premixing the weighted materials; Melting and dispersing the mixed mixture to prepare a chip form (S130); Grinding the manufactured chip to a predetermined size to form a powder coating (S140); And filtering and packaging the powder coating formed (S150); it can be achieved by providing a method for producing an epoxy semi-glow powder coating composition for the engine block comprising a.

Further, in the step of weighing the constituent material (S110), 20 to 80 parts by weight of epoxy resin having an epoxy equivalent of 500 to 2000 g / eq and an epoxy equivalent of 50 to 200 with respect to the total weight of the epoxy semi-glow powder coating composition for the engine block 1 to 10 parts by weight of the first epoxy curing agent is g / eq; 0.5 to 10 parts by weight of a second epoxy curing agent having an epoxy equivalent of 20 to 100 g / eq; 1 to 10 parts by weight of a special curing agent having an epoxy equivalent of 200 to 500 g / eq; 0.1 to 2 parts by weight of a curing accelerator; 5 to 60 parts by weight of inorganic filler; And 0.1 to 15 parts by weight of the additive; may be characterized in that the basis weight.

On the other hand, an object of the present invention is the step of pre-treating the subject (S210); Painting the epoxy semi-glow powder coating material for the engine block on the pretreated material (engine block cylinder) by an electrostatic spray coating method (S220); Drying the epoxy semi-glow powder coating for the engine block by using a hot air drying furnace (S230); And cooling the subject (S240). It can be achieved by providing a coating method of an epoxy semi-glow powder coating composition for an engine block.

According to one embodiment of the present invention, when the coating film is formed on the outer surface of the engine block using the epoxy semi-glow powder coating for the engine block of the present invention, it is excellent in adhesion to the subject, salt water spray resistance (corrosion resistance), In addition to excellent chemical properties, there is no generation of VOC (volatile organic compounds) during the manufacturing, painting, and drying of the paint, and the use of powder paint as an environmentally friendly paint, in which no harmful substances are detected even during the dissolution test of the coating film. This has the effect of expanding the range.

Hereinafter, preferred embodiments of the present invention will be described in detail. In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

<Powder coating composition>

The epoxy semi-glow powder coating composition (hereinafter, referred to as a powder coating composition) for engine block coating of the present invention comprises an epoxy resin, a first epoxy curing agent, a second epoxy curing agent, a special curing agent, a curing accelerator, an inorganic filler, and an additive.

The epoxy resin in this invention uses a BPA type epoxy resin. In addition, epoxy resins having an equivalent weight of 500 to 2000 g / eq are used. Here, when the equivalent of epoxy resin is less than 500 g / eq, there exists a problem in the storage property and chipping property of a coating material, and when the equivalent of epoxy resin exceeds 2000 g / eq, there exists a problem in the appearance and productivity of a coating film.

On the other hand, in order to prevent deterioration of the appearance of the coating film, to improve the chipping property of the cured coating film after coating, to improve the productivity, and to secure the physical properties of the powder coating composition, the equivalent weight is 2000 g / eq to the epoxy resin of 500 g / eq or more and 2000 g / eq or less. You may mix and use the epoxy resin more than eq and 3000 g / eq or less. In this case, the mixing ratio of the epoxy resin having an equivalent weight of 500 g / eq or more and 2000 g / eq or less and the epoxy resin having an equivalent weight of more than 2000 g / eq 3000 g / eq or less may be 1: 1 to 9: 1, and preferably 5: 1 to 9: 1.

In addition, the epoxy resin may be included in 20 to 80 parts by weight, preferably 45 to 70 parts by weight based on the total weight of the powder coating composition. This is to prevent the external appearance of the coating film, to improve productivity and to secure the physical properties of the coating film. That is, if the content of the epoxy resin is less than 20 parts by weight, there is a problem of deterioration of adhesion to the coating and the appearance of the coating film, and if the content of the epoxy resin is more than 80 parts by weight, the productivity is lowered and the edge cover ability is inferior. there is a problem.

The curing agent is used to cure the epoxy resin, and the curing agent in the present invention includes a first epoxy curing agent having an epoxy equivalent of 50 to 200 g / eq, a second curing agent having an equivalent of 20 to 100 g / eq and an equivalent of 200 to A special hardener of 500 g / eq is used. Here, the first curing agent is an amine curing agent, the second curing agent is a dicyandiamide (DICY) curing agent, the special curing agent is a carboxylic functional acrylic resin curing agent having a carboxyl functional group. As such, two or more curing agents may be used to adjust the gloss, gel time, and curing conditions. If only one type of curing agent is used, the desired gloss and curing conditions cannot be satisfied.

In addition, the total weight of the powder coating composition, it is preferable that the first hardener comprises 1 to 10 parts by weight, the second hardener comprises 0.5 to 10 parts by weight, and the special curing agent 1 to 10 parts by weight. This causes the problem of uncuring when the first hardener is less than 1 part by weight, the second hardener is less than 0.5 part by weight and the special hardener is less than 1 part by weight, and the first hardener, the second hardener and the special hardener are more than 10 parts by weight. This is because a problem of deteriorating the physical properties of the coating film occurs.

On the other hand, the use of such a curing agent has the effect of improving the excellent adhesion with the engine cylinder block, salt water spray resistance and hardness.

As the inorganic filler, one or two or more of barium sulfate, calcium carbonate, silica, magnesium hydroxide, alumina hydroxide, titanium dioxide, cray, alumina, mica, wollastonite, and talc may be used. Also, preferably, the particle size of the inorganic filler may be 0.1 to 10㎛. If the particle size of the inorganic filler is less than 0.1 μm, agglomeration occurs in the mixing process during preparation of the powder coating composition, resulting in poor dispersibility. On the contrary, when the particle size exceeds 10 μm, the appearance and coating properties of the coating film are deteriorated.

In addition, the inorganic filler may be used 5 to 60 parts by weight, preferably 30 to 50 parts by weight, based on the total weight of the powder coating composition. If the inorganic filler is less than 5 parts by weight, there is a problem of sagging of the coating film and a reduction in hiding power, and if it exceeds 60 parts by weight, the content of the resin component is relatively decreased, thereby greatly reducing physical properties.

A hardening accelerator is used to accelerate hardening of an epoxy resin, and what has a functional group which has the effect of promoting hardening at the terminal group is used. That is, the curing accelerator in the present invention may be selected from amines, imidazoles, B.P.O (Benzoyl Peroxide), or a mixture thereof. Herein, 2-methyl imidazole may be used as the imidazole, and amine adduct may be used as the amine.

In addition, the curing accelerator, based on the total weight of the powder coating composition, 0.1 to 2 parts by weight may be used, preferably 0.2 to 0.5 parts by weight may be used. This is because when the inorganic filler is less than 0.1 part by weight, the curing time may be long, which may cause a problem in curing of the paint.

Powder coating composition comprises an additive. The additive is used for the purpose of preventing bubbles, preventing cratering of the coating film, preventing pinholes, and controlling flowability. Additives include coloring pigments that give color to coatings, dispersants to enhance the dispersion effect of resins and pigments, gloss regulators to control the glossiness of coatings, flow prevention during melting of paints, and hydrophilic and hydrophobic systems to improve fluidity of paint powders. Fumed silica, polyethylene, polypropylene and polyamide waxes, acrylic additives, other thermoplastic resins, and the like can be used, and are not limited to these additives for various purposes.

The most important additive in the present invention is an antifoam additive. Since the object to be painted (engine block) is made of cast iron or aluminum casting, it contains a large amount of pores in the casting. Therefore, when a general paint is used, bubbles are generated in the cured coating film. In order to solve this problem, it is preferable to use an antifoaming additive.

In addition, the additive is appropriately used depending on the intended use, and is preferably included in an amount of 0.1 to 15 parts by weight based on the total weight of the powder coating composition. If the content of the additive is less than 0.1 parts by weight, it is not possible to obtain an appropriate effect according to the use of the additive, and even if it exceeds 15 parts by weight, there is no increase in the effect, which is uneconomical, and in some cases, it may cause a decrease in productivity and appearance of the coating film. Because.

<Method for Producing Powder Coating Composition>

The method for preparing the powder coating composition includes step A of weighing the constituent materials of the powder coating composition, step B of premixing the weighed materials, step C of melting and dispersing the mixed mixture into chips, and preparing the chip in a predetermined size. D step of pulverizing to form a powder coating, and E step of filtering and packaging the powder coating formed. Hereinafter, each step will be described in detail.

First, in step A, an epoxy resin, a first hardener, a second hardener, a special hardener, an inorganic filler, a hardening accelerator, a coloring pigment, and other additives are weighed with an electronic balance and introduced into a premixer (S110). Here, the amount of each constituent material to be metered and mixed is 20 to 80 parts by weight of an epoxy resin having an epoxy equivalent of 500 to 2000 g / eq and an epoxy equivalent of 50 to 200 g / eq based on the total weight of the powder coating composition. 1 to 10 parts by weight of a curing agent, 0.5 to 10 parts by weight of a second epoxy curing agent having an epoxy equivalent of 20 to 100 g / eq, and 1 to 10 parts by weight of a special curing agent having an epoxy equivalent of 200 to 500 g / eq; The weight of the curing accelerator is 0.1 to 2 parts by weight, the inorganic filler 5 to 60 parts by weight, and the additives 0.1 to 15 parts by weight of the basis weight is added to the premixer.

Next, the components mixed in the premixer are stirred and mixed uniformly (S120).

Next, the pre-mixed mixture is melt-dispersed at a temperature of 70 to 130 ° C. using a melt screw (twin screw), and a chip is manufactured to a thickness that does not cause a problem in grinding (S130).

Next, the manufactured chip is pulverized using a high speed grinder. At this time, by controlling the particle size of the powder coating in the grinding process to have an average particle of 20 to 50㎛ (S140).

Finally, the pulverized paint particles are filtered using a sieve of 70 to 180 μm, and packed after inspection to complete the powder coating composition (S150).

The powder coating composition prepared by such a manufacturing process has a glass transition temperature (Tg) of 40 to 70 ℃, preferably 45 to 55 ℃, gelation time 30 to 150 (sec), preferably 30 to 70 ( sec). In addition, the minimum melt viscosity of the paint has a 60 to 110 poise (Poise). This is not preferable because the glass transition temperature is less than 40 ℃ flow is better, the corner wetting properties of the engine block is better, but the storage properties are lowered, and if the glass transition temperature is above 70 ℃ storage properties are good but the coating material Because of poor wetting, the control of the glass transition temperature is important.

In addition, when the gelation time is less than 30 (sec), the curing conditions are favorable, but the wettability of the paint is deteriorated, so that the appearance defects and the corner penetration paintability are deteriorated. Because it can be uncured in the line. Therefore, the gelation time needs to be very importantly controlled.

In addition, if the minimum melting point is less than 60 poise, the coating phenomenon may occur, and if it exceeds 110 poise, there is a problem in that the corner penetration coating property is deteriorated.

Therefore, the powder coating composition according to the present invention has such a glass transition temperature, gelation time, minimum melt viscosity, and the flowability, wettability, and curability of the coating film when painting the engine block in the coating line is not only suitable for the coating operation. It shows good shelf life.

<Coating Method of Powder Coating Composition>

The powder coating composition is coated on an engine cylinder block made of cast iron casting or aluminum casting through a special coating process to form a coating film. At this time, the coating process selects varieties of paints in consideration of the purpose of use, types of coatings, and coating conditions, and determines the method of painting and drying method based on the relationship between the selected paints and the coatings.

Coating process of the powder coating composition is a step of pre-treating the subject (S210), the step of painting the epoxy semi-glow powder coating for the engine block by the electrostatic spray method (S220), the painted engine block The epoxy semi-glow powder coating for drying using a hot air drying furnace (S230) and the step of cooling the target (S240).

First, the coating method of the coating composition is carried out using the electrostatic spray coating method in a specially produced coating line. In such a coating method, first, a surface of an object to be formed (engine block) to form a coating film (shot blast, etc.) to increase the adhesion of the coating film formed in the next step (S210).

Next, the pretreated engine block is moved horizontally by the conveyor belt, and at the same time, the outer surface of the engine block is painted using an electrostatic spray gun (S220).

Next, it is cured and dried using a hot air drying furnace (S230). At this time, the setting temperature of the drying furnace is preferably 230 to 270 ℃, the drying furnace passing time is preferably 30 to 40 minutes. If the setting temperature is too low or the transit time is too short, the problem of uncured film Occurs, and if the setting temperature is too high or the drying time is too long, Because it occurs.

Finally, the cooling of the subject after passing through the drying furnace is natural cooling or forced cooling (S240), and the coated subject undergoes a subsequent process after the intermediate inspection.

After coating the powder coating composition on the coated material by this process, the fully cured coating film has excellent adhesion with the coated material, and the coating film does not peel off during friction, and it is resistant to salt spraying, chipping, bubble prevention, and chemical resistance. This is excellent. In addition, there is no VOC (volatile organic compound) generation as in the liquid coating, there is an advantage that no environmentally harmful components are detected even in the dissolution test of the coating film. As a result, it is preferably applicable to the engine block.

Hereinafter, the present invention will be described in more detail with reference to the following examples. These examples are only examples for the present invention, and the present invention is not limited thereto.

[Examples and Comparative Examples]

To prepare an epoxy semi-glow powder coating composition for the engine block coating using the composition of Table 1.

First, it was added to a premixer after the basis weight so as to have the compounding ratio shown in Table 1, and cross-mixed at a low speed of 1500 RPM and a high speed of 4000 RPM. The mixture thus obtained was poured into a melt screw (ZSK-70) and melt dispersed at 100 ° C. The melt dispersion obtained through the melt spreader was manufactured in the form of a chip having a thickness of 1 to 3 mm and a length of 5 to 20 mm after cooling through a chill roller and a cooling belt. The chip prepared here was pulverized using an ACM60 grinder, and the pulverized powder was sieved to prepare an epoxy semi-glow powder coating composition for an engine block having an average particle of 30 to 50 μm.

division Example Comparative example One 2 3 One 2 3 4





Ingredient
Epoxy resin A 50 - - - - - 50 B 50 90 80 70 70 100 50 C - - 20 - - - - D - 10 - - - - -
Epoxy curing agent A - - 5 5 6 6 7 B 4 3 2 - - 2 One C 6 6 2 - - - - Polyester resin A - - - 30 - - - B - - - - 30 - - Hardening accelerator A - - 0.5 - - - - Pigment A One One One One One One One Inorganic fillers A 15 15 15 20 20 20 20 additive A 6 6 6 - - 6 6
1) epoxy resin A-Epoxy equivalent weight: 600g / eq,
2) epoxy resin B-Epoxy equivalent weight: 800g / eq,
3) epoxy resin C-Epoxy equivalent weight: 1200g / eq,
4) epoxy resin D-Epoxy equivalent weight: 2600g / eq,
5) epoxy curing agent A-Epoxy equivalent weight: 100g / eq,
6) epoxy curing agent B-Epoxy equivalent weight: 40g / eq,
7) epoxy curing agent C-Epoxy equivalent weight: 400g / eq,
8) polyester resin A-Acid value: 70mg KOH / g,
9) polyester resin B-Acid value: 50mg KOH / g,
10) Hardening accelerator A-imidazole type accelerator
Pigment A-Carbon black, Average particle 1 ~ 5um
12) Inorganic fillers-Calcium carbonate or Barium sulfate, average particle size: 1 ~ 10um
13) Additives-Antifoaming Agent (PE or PP)

[Measurement Result of Powder Coating Composition]

The physical property measurement results of the epoxy semi-glow powder coating composition for an engine block prepared in Examples and Comparative Examples of Table 1 are shown in Table 2 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Average particle size 38 ~ 40㎛ 35 ~ 40㎛ 35 ~ 40㎛ 35 ~ 40㎛ 35 ~ 40㎛ 35 ~ 40㎛ 35 ~ 40㎛ Gel time
(180 ℃) 38 seconds 44 seconds 51 seconds 79 seconds 111 seconds 101 seconds 89 seconds Minimum melt viscosity
(Poise) 65 95 91 82 89 94 72 Paint Tg (℃) 42 45 46 46 48 47 45 Coating film Tg (℃) 85 86 83 77 78 79 77

The average particle size of the paint should be appropriate for the coating surface wetting of the paint and the corner penetration coating of complex structures. The gelation time of the paint should be short due to the characteristics of the engine block painting work that needs to be hardened in a short time due to the coating on a thick object, and the minimum melt viscosity of the paint is important for giving the paint wettability of the paint to the engine block. The higher the glass transition temperature (Tg) of the coating film, the more advantageous for the processability.

[Preparation and Physical Property Test of Epoxy Powder Coating Composition for Engine Block]

Specimens were prepared using an epoxy semi-glow powder coating material for engine blocks prepared according to Examples and Comparative Examples of the present invention, and the physical properties were tested in the following manner and shown in Table 3.

1) Production of coating specimen

① Specimen condition-75mm × 150mm × 0.7mm thick steel plate and engine block.

② Coating method-After pretreatment of the prepared specimens by appropriate method, and after coating with coating thickness of 60 ~ 80㎛ by electrostatic spray coating method, it is cured by using hot air drying furnace.

(10 min-subject temperature at 160 ° C.) and then cooled.

2) Property test method

<Impact resistance> According to KSD 6711 test method

<Hot resistance> According to KSM5000, 3411 test method

<Salt Spray Resistance> According to KSD 9502 Test Method

<Glass Transition Temperature> According to CAN / CSA 245.2 Test Method

<Adhesion> According to the KSM ISO 2409 test method

Example Comparative example One 2 3 One 2 3 4 Impact resistance ○ ○ ○ △ △ △ △ Adhesion ○ ○ ○ △ △ ○ ○ Hot water resistance ○ ○ ○ ○ △ × △ Salt water spray resistance ○ ○ ○ △ △ △ ○ Corner Penetration Coating ○ ○ ○ △ ○ ○ × Bubble, pinhole ○ ○ ○ △ △ ○ ○ Environmental hazard ○ ○ ○ ○ ○ ○ ○ ○: good, △: insufficient, ×: defective

Table 3 shows the results of physical property test after preparing the powder coating composition under the same conditions as in Table 1. As shown in Table 3, the measurement results of the physical properties of the examples of the present invention showed better results than the comparative examples.

Examples 1 to 3 were hot water resistance tests, which were good in adhesion measured after heating for 1 hour in 98 ± 2 ° C. water. On the other hand, Comparative Examples 2 and 3 were difficult to shorten the curing rate, and thus were not suitable for the required physical properties of the engine block to be cured in a short time.

In addition, Examples 1 to 3 were saline spray resistance tests, and after the test for 500 hours in a tester sprayed with a 5% aqueous NaCl solution at 35 ° C., the measured rust and peeling conditions were good.

In addition, in Examples 1 to 3, even in the corner penetration coating test conducted by coating test on the engine cylinder block, good results were obtained in curing rate, viscosity of paint and paint wetting.

In addition, in Examples 1 to 3, even in the appearance comparison of the coated cured coating film, the effect of preventing air bubbles and pinholes was better than that of the comparative example.

On the other hand, Examples 1 to 3 are environmentally friendly paints containing no heavy metals, and the dissolution test showed no elution of harmful substances.

While the technical spirit of the present invention has been described above, it is intended to be illustrative of the best embodiment of the present invention and not to limit the present invention. In addition, it is obvious that any person skilled in the art may make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (11)

Regarding the total weight of the epoxy semi-glow powder coating composition for the engine block,
20 to 80 parts by weight of an epoxy resin having an epoxy equivalent of 500 to 2000 g / eq;
1 to 10 parts by weight of the first epoxy curing agent having an epoxy equivalent of 50 to 200 g / eq;
0.5 to 10 parts by weight of a second epoxy curing agent having an epoxy equivalent of 20 to 100 g / eq;
1 to 10 parts by weight of a special curing agent having an epoxy equivalent of 200 to 500 g / eq;
0.1 to 2 parts by weight of a curing accelerator;
5 to 60 parts by weight of inorganic filler; And
Additive 0.1 to 15 parts by weight; Epoxy semi-light powder coating composition for an engine block comprising a.
The method of claim 1,
The first epoxy curing agent is an amine curing agent,
The second epoxy curing agent is a dicyandiamide (DICY) curing agent,
The special curing agent is an epoxy semi-glow powder coating composition for an engine block, characterized in that at least any one selected from the group consisting of a curing agent (Carboxylic functional acrylic resin) having a carboxyl functional group.
The method of claim 1,
The curing accelerator is any one selected from the group consisting of an imidazole compound, an amine compound and mixtures thereof Epoxy semi-light powder coating composition for an engine block.
The method of claim 1,
The inorganic filler is any one selected from the group consisting of barium sulfate, calcium carbonate, silica, titanium dioxide, magnesium hydroxide, alumina hydroxide, cray, mica, alumina, wollastonite, talc and mixtures thereof. Epoxy semi-gloss powder coating composition.
The method of claim 1
The coloring pigment is an epoxy semi-glow powder composition for an engine block, characterized in that any one selected from the group consisting of bismuth vanadate, cyanine green, cyanine blue, iron oxide, iron oxide, carbon black, Naver blue and mixtures thereof.
The method of claim 1,
The epoxy semi-glow powder coating composition for the engine block,
Additive 0.1 to 15 parts by weight; Epoxy semi-light powder coating composition for an engine block further comprising.
The method of claim 1,
The epoxy semi-glow powder coating composition for the engine block,
Epoxy semi-glow powder coating composition for an engine block further comprising; epoxy resin having an epoxy equivalent of more than 2000 g / eq 3000 g / eq or less.
8. The method of claim 7,
The epoxy semi-glow powder coating composition for the engine block,
Epoxy resin which the said equivalent is 500 g / eq or more and 2000 g / eq or less,
Epoxy semi-glow powder coating composition for an engine block comprising an epoxy resin having an equivalent weight of more than 2000 g / eq and less than 3000 g / eq in a ratio of 1: 1 to 9: 1.
Weighing the constituent materials of the epoxy semi-glow powder coating composition for an engine block (S110);
Premixing the weighted materials (S120);
Melting and dispersing the mixed mixture to produce a chip form (S130);
Grinding the manufactured chip to a predetermined size to form a powder coating (S140); And
Filtering and packaging the formed powder coating (S150); Method for producing an epoxy semi-glow powder coating composition for an engine block comprising a.
The method of claim 9,
In the step of weighing the constituent material (S110),
Regarding the total weight of the epoxy semi-glow powder coating composition for the engine block,
20 to 80 parts by weight of an epoxy resin having an epoxy equivalent of 500 to 2000 g / eq, and 1 to 10 parts by weight of a first epoxy curing agent having an epoxy equivalent of 50 to 200 g / eq; 0.5 to 10 parts by weight of a second epoxy curing agent having an epoxy equivalent of 20 to 100 g / eq; 1 to 10 parts by weight of a special curing agent having an epoxy equivalent of 200 to 500 g / eq; 0.1 to 2 parts by weight of a curing accelerator; 5 to 60 parts by weight of inorganic filler; And 0.1 to 15 parts by weight of additives.
Pre-treating the subject (S210);
Painting an epoxy semi-glow powder coating material for an engine block on the pretreated material (engine block cylinder) by an electrostatic spray coating method (S220);
Drying the coated semi-gloss powder coating for the engine block using a hot air drying furnace (S230); And
Cooling the subject (S240); The coating method of the epoxy semi-light powder coating composition for an engine block comprising a.