Epoxy coating composition

Abstract

The present invention relates to an epoxy coating composition having excellent physical properties under various curing conditions.

Description

Technical Field

[0001] The present invention relates to an epoxy coating composition having excellent physical properties under various curing conditions. Background Art

[0002] Steel pipes for gas are coated with various coatings to protect the inside during storage, construction, and gas transportation. Epoxy coatings or powder coatings with various physical properties are proposed according to the use of the steel pipe. As an example, Patent No. 2118945 discloses an epoxy resin coating for steel pipes, which contains BPA type epoxy resin, BPF type epoxy resin, isocyanate prepolymer, color pigment, extender pigment, zirconium powder, sericite powder, and solvent in a specific mixing ratio.

[0003] Since such solvent-based epoxy coatings generate a lot of volatile organic compounds (VOC), there is an increasing demand for high-solid content solvent-based epoxy coatings or water-soluble epoxy coatings in order to reduce environmental pollution. However, high-solid content solvent-based epoxy coatings or water-soluble epoxy coatings have so far had limitations such as difficulty in ensuring physical properties that can replace existing solvent-based epoxy coatings.

[0004] In addition, solvent-free epoxy coatings are being developed as an alternative to solvent-based epoxy coatings, but existing solvent-free coatings do not fully ensure the physical properties required of coatings, such as flexibility, hardness, water resistance, and rust resistance. In particular, existing solvent-free coatings can only exhibit the specified physical properties under limited curing conditions, so it is necessary to develop coatings that have excellent physical properties under a variety of curing conditions. Summary of the invention

[0005] (Problems to be solved by the invention)

[0006] The present invention provides an epoxy coating composition having excellent physical properties under a wide range of curing temperature conditions.

[0007] (Measures taken to solve the problem)

[0008] The invention provides a solvent-free two-component epoxy coating composition, which comprises: a main agent comprising an epoxy resin, a reactive diluent, an extender pigment and an organosilicon resin; and a curing agent comprising an amine, an amide resin and a non-reactive diluent.

[0009] (Effects of the Invention)

[0010] The present invention provides a solvent-free two-component epoxy coating composition having excellent physical properties under a wide range of curing temperature conditions. The coating composition of the present invention is a solvent-free type, and provides a coating film having good environmental protection and excellent flexibility, hardness, water resistance and rust resistance. The epoxy coating composition of the present invention can be used as a coating for gas steel pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The evaluation criteria for water resistance of the coating film are shown. DETAILED DESCRIPTION

[0012] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following content, and each component can be variously deformed or selectively mixed as required. Therefore, it should be understood that all changes, equivalents or substitutes included in the thought and technical scope of the present invention are included.

[0013] The "viscosity" used in this specification is measured by conventional methods known in the art, for example, it can be measured using a Brookfield viscometer at room temperature (25°C). The "particle size (D50)" is measured by conventional methods known in the art, for example, it can be measured by a laser particle size analyzer. The "weight average molecular weight" is measured by conventional methods known in the art, for example, it can be measured by a gel permeation chromatography (GPC) method.

[0014] The solvent-free two-component epoxy coating composition of the present invention comprises: a main agent, which comprises an epoxy resin, a reactive diluent, an extender pigment and an organosilicon resin; and a curing agent, which comprises an amine, an amide resin and a non-reactive diluent. The epoxy coating composition of the present invention may further comprise additives such as an anti-settling agent, a matting agent, an anti-skinning agent, a dispersant, a waterproofing agent, a leveling agent, a drying accelerator, a defoaming agent, an antibacterial agent, a water repellent, and a moisture-proof agent as required.

[0015] <Main agent>

[0016] Epoxy resin

[0017] The main agent of the epoxy coating composition of the present invention comprises an epoxy resin. The epoxy resin may comprise a first epoxy resin and a second epoxy resin, wherein the first epoxy resin comprises a bisphenol A epoxy resin and the second epoxy resin comprises a phenol novolac epoxy resin. When the first epoxy resin and the second epoxy resin are mixed, the bending resistance and water resistance of the coating film can be further improved.

[0018] The viscosity (25°C) of the first epoxy resin may be 10,000 to 15,000 cPs, for example, 11,500 to 13,500 cPs, and the epoxy equivalent may be 150 to 220 g / eq, for example, 184 to 194 g / eq. When the viscosity (25°C) of the first epoxy resin is less than the aforementioned range, the viscosity decreases, and thus the physical properties decrease. When the viscosity exceeds the aforementioned range, the viscosity increases, and thus the workability decreases. When the epoxy equivalent of the first epoxy resin deviates from the aforementioned range, the coating film properties decrease.

[0019] Based on the total amount of the main agent, the first epoxy resin may be included in an amount of 30 to 50 wt %, for example, 35 to 45 wt %. If the content of the first epoxy resin is less than the above range, the bending resistance may be poor, and if it exceeds the above range, the solvent resistance may be poor.

[0020] The viscosity (25° C.) of the second epoxy resin may be 15,000 to 35,000 cps, such as 20,000 to 30,000 cps, and the epoxy equivalent may be 130 to 220 g / eq, such as 155 to 195 g / eq. When the epoxy equivalent of the second epoxy resin is less than the above range, the solvent resistance may be reduced, and when it exceeds the above range, the flexibility may be reduced.

[0021] Based on the total amount of the main agent, the second epoxy resin may be included in an amount of 1 to 25 wt %, for example, 5 to 20 wt %. When the content of the second epoxy resin is less than the above range, the solvent resistance may be deteriorated, and when it exceeds the above range, the bending resistance may be deteriorated.

[0022] Reactive diluent

[0023] The main agent of the epoxy coating composition of the present invention includes a reactive diluent. As the above-mentioned reactive diluent, a difunctional diglycidyl ether (Diglycidyl Ether) type reactive diluent can be used. As the difunctional diglycidyl ether, 1,4-butanediol diglycidyl ether (1,4-Butanediol diglycidyl ether), neopentyl glycol diglycidyl ether (Neopentyl Glycol Diglycidyl Ethers), 1,6-hexanediol diglycidyl ether (1,6-Hexanediol Diglycidyl Ether) and the like can be used. The above-mentioned difunctional diglycidyl ethers can be used alone or in combination of two or more.

[0024] The reactive diluent may have a viscosity (at 25° C.) of 10 to 20 cps, and an epoxy equivalent of 100 to 150 g / eq.

[0025] The reactive diluent may be contained in an amount of 2 to 15% by weight, for example, 2 to 8% by weight, based on the total amount of the main agent. When the reactive diluent content is less than the above-mentioned range, the viscosity will increase, thereby reducing the workability. When the reactive diluent content exceeds the above-mentioned range, the viscosity will decrease, thereby improving the workability, but the physical properties of the coating will decrease.

[0026] Extender Pigment

[0027] The main agent of the epoxy coating composition of the present invention includes a body pigment. The body pigment plays a role in improving the physical properties of the coating film. As the above-mentioned body pigment, silicon dioxide, talc, calcium carbonate, magnesium carbonate, barium sulfate, etc. can be used. The above-mentioned body pigment can be used alone or in combination of two or more.

[0028] The extender pigment may be contained in an amount of 20 to 50 wt %, for example, 30 to 45 wt %, based on the total amount of the main agent. When the extender pigment content is within the above range, the mechanical properties of the coating film can be improved.

[0029] Silicone resin

[0030] The main agent of the epoxy coating composition of the present invention comprises an organosilicon resin. The organosilicon resin plays a role in improving the flexibility of the coating film. As the organosilicon resin, polysiloxane or the like can be used, and as an example, methyl silsesquioxane or the like can be used. The organosilicon resin has a hollow structure and is cross-linked with the epoxy resin to form pores in the coating, thereby improving flexibility and adhesion.

[0031] The solid content of the above-mentioned silicone resin is 90 to 100%, the average particle size (D50) can be 2 to 12 μm, for example, 4 to 8 μm, the flash point can be 100 to 200° C., for example, 120 to 150° C., and the weight average molecular weight can be 500 to 700 g / mol, for example, 550 to 650 g / mol. In the case where the average particle size of the above-mentioned silicone resin is smaller than the above-mentioned range, the effect of silicone is insufficient, and the viscosity is reduced, so that the workability and bendability are reduced. In the case of exceeding the above-mentioned range, it becomes too thick (bulky) to increase the viscosity of the coating, and the hard and brittle (brittle) property is enhanced, so that the bendability and workability are reduced. In the case where the flash point is lower than the above-mentioned range, the soft property is enhanced, so that the adhesive force is reduced. In the case of exceeding the above-mentioned range, the hard property is enhanced, so that the bendability is reduced.

[0032] Based on the total amount of the main agent, the above-mentioned silicone resin may be included in an amount of 0.1 to 3 wt %, for example, 0.1 to 1 wt %. When the content of the above-mentioned silicone resin is less than the above-mentioned range, the effect of the silicone decreases, thereby reducing the flexibility. When the content exceeds the above-mentioned range, the workability decreases.

[0033] The epoxy resin and the silicone resin may be used in a mixing ratio (weight ratio) of 1:0.1 to 2, for example, in a mixing ratio (weight ratio) of 1:0.5 to 1. When the mixing ratio of the silicone resin to the epoxy resin is less than the aforementioned range, the effect of the silicone is insufficient, and the bendability is reduced. When the mixing ratio exceeds the aforementioned range, the hard and brittle property is enhanced, and the bendability and workability are reduced.

[0034] <Curing Agent>

[0035] amine

[0036] The curing agent of the epoxy coating composition of the present invention comprises an amine. The above-mentioned amine may comprise polyoxypropylene diamine, modified aliphatic amine, modified alicyclic amine, etc. The above-mentioned amine may be used alone or in combination of two or more. As an example, the above-mentioned amine comprises polyoxypropylene diamine, modified aliphatic amine and modified alicyclic amine. When the above-mentioned three amines are used in combination, the bending resistance, rust resistance, water resistance and drying property of the coating film can be further improved.

[0037] The active hydrogen equivalent of the polyoxypropylene diamine may be 40 to 80 g / eq, for example, 50 to 70 g / eq. If the active hydrogen equivalent of the polyoxypropylene diamine is out of the above range, the bendability may be reduced.

[0038] The amine value of the modified aliphatic amine can be 300 to 450 mgKOH / g, for example, 360 to 420 mgKOH / g. As an example, meta-xylene diamine can be used. When the amine value of the modified aliphatic amine is out of the above-mentioned range, the hardness of the coating film will decrease.

[0039] The amine value of the modified alicyclic amine may be 250 to 400 mgKOH / g, for example, 290 to 340 mgKOH / g. As an example, isophorone diamine may be used. When the amine value of the modified alicyclic amine is less than the above-mentioned range, the drying property may be reduced, and when it exceeds the above-mentioned range, the bendability may be reduced.

[0040] Based on the total amount of the curing agent, 6 to 20% by weight of the polyoxypropylene diamine, 5 to 15% by weight of the modified aliphatic amine, and 35 to 50% by weight of the modified alicyclic amine may be included. When the content of the polyoxypropylene diamine is less than the above-mentioned range, the flexibility will be reduced, and when it exceeds the above-mentioned range, the rust resistance and solvent resistance will be reduced. When the content of the modified aliphatic amine is less than the above-mentioned range, the hardness of the coating film will be reduced, and when it exceeds the above-mentioned range, the flexibility will be reduced. When the content of the modified alicyclic amine is less than the above-mentioned range, the rust resistance and solvent resistance will be reduced, and when it exceeds the above-mentioned range, the flexibility will be reduced.

[0041] Amide resin

[0042] The curing agent of the epoxy coating composition of the present invention contains an amide resin. The amide resin contains an acyl group in the resin structure and plays a role in improving the flexibility of the coating film.

[0043] The solid content of the amide resin may be 90 to 100%, for example, 95 to 100%, the viscosity (25°C) may be 300 to 700 cPS, for example, 400 to 600 cPS, the active hydrogen equivalent may be 75 to 105 g / eq, for example, 85 to 95 g / eq, and the amine value may be 300 to 600 mgKOH / g, for example, 400 to 500 mgKOH / g. In the case where the solid content of the amide resin is less than the aforementioned range, the mechanical properties may be reduced, and in the case where the viscosity is out of the aforementioned range, the workability may be reduced. In the case where the active hydrogen equivalent of the amide resin is out of the aforementioned range, the water resistance, corrosion resistance and rust resistance may be reduced, and in the case where the amine value is out of the aforementioned range, the flexibility of the coating may be reduced.

[0044] As the amide resin, tetraethylenepentamine (TEPA) amide resin, triethylenetetramine (TETA) amide resin, and the like can be used.

[0045] Based on the total amount of the curing agent, the amide resin may be contained in an amount of 3 to 20 wt %, for example, 5 to 15 wt %. When the content of the amide resin is less than the above range, the bendability may be reduced, and when it exceeds the above range, the water resistance and rust resistance may be reduced.

[0046] The amine and the amide resin may be used in a mixing ratio (weight ratio) of 1:0.01 to 2, for example, in a mixing ratio (weight ratio) of 1:0.1 to 0.5. When the mixing ratio of the amide resin to the amine is less than the above range, the bendability may be reduced, and when it exceeds the above range, the water resistance and rust resistance may be reduced.

[0047] Non-reactive diluent

[0048] The curing agent of the epoxy coating composition of the present invention contains a non-reactive diluent. The non-reactive diluent plays a role in adjusting the viscosity of the coating composition.

[0049] As the non-reactive diluent, benzyl alcohol, dodecylphenol, etc. can be used. The non-reactive diluent can be used alone or in combination of two or more.

[0050] The non-reactive diluent may be contained in an amount of 5 to 40% by weight, for example, 10 to 30% by weight, based on the total amount of the curing agent. When the content of the non-reactive diluent is less than the above-mentioned range, the viscosity will increase, thereby reducing the workability. When the content exceeds the above-mentioned range, the viscosity will decrease, thereby improving the workability, but the physical properties of the coating will decrease.

[0051] The two-component epoxy coating composition of the present invention may contain 20 to 50 parts by weight of the curing agent based on 100 parts by weight of the main agent.

[0052] Modes for carrying out the invention

[0053] Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are only provided to help understanding of the present invention, and the scope of the present invention is not limited to the examples in any sense.

[0054] [Experimental Example 1-13]

[0055] The main agent and the curing agent were prepared according to the compositions described in Tables 1 and 2 below, and the main agent and the curing agent were mixed at a weight ratio of 2.9:1 to prepare the coating composition of each experimental example.

[0056] [Table 1]

[0057]

[0058] [Table 2]

[0059]

[0060] [Main agent]

[0061] Epoxy resin 1-1: BPA epoxy resin (viscosity (25°C) 12,000 cps, epoxy equivalent 190 g / eq)

[0062] Epoxy resin 1-2: BPA epoxy resin (viscosity (25°C) 13,000 cps, epoxy equivalent 185 g / eq)

[0063] Epoxy resin 1-3: BPA epoxy resin (viscosity (25°C) 11,000 cps, epoxy equivalent 230 g / eq)

[0064] Epoxy resin 1-4: alicyclic epoxy resin (viscosity (25°C) 12,000 cps, epoxy equivalent weight 200 g / eq)

[0065] Epoxy resin 2-1: phenolic novolac resin (viscosity (25°C) 22,000 cps, epoxy equivalent 160 g / eq)

[0066] Epoxy resin 2-2: phenol novolac resin (viscosity (25°C) 27,000 cps, epoxy equivalent 190 g / eq)

[0067] Epoxy resin 2-3: phenol novolac resin (viscosity (25°C) 25,000 cps, epoxy equivalent weight 250 g / eq)

[0068] Extender pigment: silica

[0069] Silicone resin 1: methyl silsesquioxane (average particle size (D50) 6 μm, solid content 100%, flash point 125°C, weight average molecular weight 600 g / mol)

[0070] Silicone resin 2: methyl silsesquioxane (average particle size (D50) 8 μm, solid content 100%, flash point 140°C, weight average molecular weight 650 g / mol)

[0071] Silicone resin 3: methyl silsesquioxane (average particle size (D50) 15 μm, solid content 100%, flash point 120°C, weight average molecular weight 400 g / mol)

[0072] Reactive diluent: 1,6-hexanediol diglycidyl ether

[0073] Anti-settling agent: alkyl ammonium chloride salt

[0074] Leveling agent: Propylene glycol methyl ether acetate

[0075] Defoaming agent: 2,6-dimethyl-4-heptanone

[0076] [Curing agent]

[0077] Polyoxypropylene diamine: active hydrogen equivalent is 60g / eq

[0078] Modified aliphatic amine: m-xylene diamine (amine value 380 mgKOH / g)

[0079] Modified alicyclic amine: isophorone diamine (amine value 330 mgKOH / g)

[0080] Amide resin 1: Tetraethylenepentamine (TEPA) amide resin (solid content 100%, viscosity (25°C) 500cps, active hydrogen equivalent 90g / eq, amine value 450mgKOH / g)

[0081] Amide resin 2: TEPA amide resin (solid content 100%, viscosity (25°C) 500 cps, active hydrogen equivalent 85 g / eq, amine value 400 mgKOH / g)

[0082] Amide resin 3: TEPA amide resin (solid content 100%, viscosity (25°C) 500 cps, active hydrogen equivalent 120 g / eq, amine value 290 mgKOH / g)

[0083] Amide resin 4: triethylenetetramine (TETA) amide resin (solid content 100%, viscosity (25°C) 500cps, active hydrogen equivalent 90g / eq, amine value 450mgKOH / g)

[0084] Non-reactive diluent: benzyl alcohol

[0085] [Physical property evaluation]

[0086] The physical properties of the coating composition prepared according to each experimental example were measured by the following methods, and the results are shown in Tables 3 and 4 below.

[0087] Flexibility

[0088] After coating, the coating composition of each experimental example was cured and dried at room temperature for 7 days. The coated portion of each dried test piece was placed in a conical mandrel bending tester with the coating facing upward and completely bent within 1 second. The maximum length of the cracked portion was measured from the end of the test piece using a magnifying glass.

[0089] [Evaluation criteria]

[0090] ◎: 8mm or less

[0091] ○: More than 8mm and less than 10mm

[0092] △: more than 10mm and less than 13mm

[0093] X: more than 13mm

[0094] hardness

[0095] After coating, the coating composition of each experimental example was cured and dried at room temperature for 7 days. After placing the dried surface of each test piece on a Buchholz hardness tester for 30 seconds, the indentation length was measured with a magnifying glass. 100 / indentation length was calculated and the hardness was evaluated according to the following criteria.

[0096] [Evaluation criteria]

[0097] ◎:More than 100

[0098] ○: 94 or more and less than 100

[0099] △: 66 or more and less than 94

[0100] X: less than 66

[0101] Water resistance

[0102] After coating, the coating composition of each experimental example was cured and dried at room temperature for 7 days. After soaking each dried test piece in water for 480 hours so that 2 / 3 of it was submerged, the state was observed with the naked eye to confirm whether blisters were generated. Thereafter, the adhesion was confirmed by cross cutting of 2 mm square and the attached Figure 1 The benchmarks were evaluated.

[0103] [Evaluation criteria]

[0104] ◎: No blisters (Blister), adhesion is 0 to 1

[0105] ○: No blisters (Blister), adhesion is 2

[0106] △: Blisters or adhesion of 3 to 5

[0107] X: Generates bubbles (Blister) with an adhesion of 3 to 5

[0108] Rust resistance

[0109] After coating, the coating composition of each experimental example was cured and dried at room temperature (25°C) for 7 days. An X-shaped scribe line was formed on the iron test piece to expose the iron test piece. After the test piece was exposed under the rust resistance test conditions (salt spray × 480 hours), the location where bubbles (Blister) were generated was measured and the maximum length was confirmed. Thereafter, a tape was pasted on the scribe line of the test piece and then peeled off to measure the maximum length of the peeled location.

[0110] [Evaluation criteria]

[0111] ◎: Blister less than 1mm, peeling less than 2mm

[0112] ○: Blister is 1 mm or more and 2 mm or less, and peeling is 2 mm or more and 3 mm or less

[0113] △: Blister exceeds 2mm or peeling exceeds 3mm

[0114] X: Blister exceeds 2mm and peeling exceeds 3mm

[0115] [Table 3]

[0116]

[0117] [Table 4]

[0118]

[0119] As shown in Tables 3 and 4 above, the coating films formed using the epoxy coating compositions of Experimental Examples 1 to 11 according to the present invention showed excellent physical properties in the overall measurement items under two curing conditions, while the coating films formed using the epoxy coating compositions of Experimental Example 12 using a silicone resin outside the scope of the present invention and Experimental Example 13 not using a silicone resin showed differences in physical properties depending on the curing conditions. In particular, the bendability was very poor under the curing condition of 150°C × 30 minutes, which means that there may be no problem immediately after coating, but problems such as cracking of the coating film may occur during the processing of the steel pipe.

[0120] (Industrial Applicability)

[0121] The present invention provides a solvent-free two-component epoxy coating composition having excellent physical properties under a wide range of curing temperature conditions. The coating composition of the present invention is a solvent-free type, which provides a coating film having good environmental protection and excellent flexibility, hardness, water resistance and rust resistance. The epoxy coating composition of the present invention can be used as a coating for gas steel pipes.

Claims

1. A solvent-free two-component epoxy coating composition comprising: A main agent, which comprises an epoxy resin, a reactive diluent, an extender pigment and an organic silicone resin; and a curing agent comprising an amine, an amide resin and a non-reactive diluent, The above-mentioned silicone resin comprises polysiloxane, The average particle size D50 of the above silicone resin is 2 to 12 μm.

2. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The epoxy resin comprises a first epoxy resin and a second epoxy resin, wherein the first epoxy resin comprises a bisphenol-A epoxy resin, and the second epoxy resin comprises a phenol novolac epoxy resin. The first epoxy resin has a viscosity of 10,000 to 15,000 cPs at 25° C. and an epoxy equivalent of 150 to 220 g / eq. The second epoxy resin has a viscosity of 15,000 to 35,000 cps at 25° C. and an epoxy equivalent of 130 to 220 g / eq. Based on the total amount of the main agent, the first epoxy resin comprises 30 to 50 weight % and the second epoxy resin comprises 1 to 25 weight % of the above-mentioned.

3. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The solid content of the above-mentioned silicone resin is 90 to 100%, the flash point is 100 to 200° C., and the weight average molecular weight is 500 to 700 g / mol.

4. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The above amines include polyoxypropylene diamine, modified aliphatic amine and modified alicyclic amine. The active hydrogen equivalent of the polyoxypropylene diamine is 40 to 80 g / eq, The amine value of the modified aliphatic amine is 300 to 450 mgKOH / g. The amine value of the modified alicyclic amine is 250 to 400 mgKOH / g. Based on the total amount of the curing agent, the present invention comprises 6 to 20 wt % of the polyoxypropylene diamine, 5 to 15 wt % of the modified aliphatic amine and 35 to 50 wt % of the modified alicyclic amine.

5. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The amide resin has a solid content of 90 to 100%, a viscosity of 300 to 700 cPS at 25° C., an active hydrogen equivalent of 75 to 105 g / eq, and an amine value of 300 to 600 mgKOH / g.

6. The solvent-free two-component epoxy coating composition according to claim 1, wherein: Based on the total amount of the main agent, the epoxy resin comprises 31 to 75 wt %, the reactive diluent comprises 2 to 15 wt %, the extender pigment comprises 20 to 50 wt % and the silicone resin comprises 0.1 to 3 wt %. Based on the total amount of the curing agent, the composition comprises 46 to 85 weight % of the above amine, 3 to 20 weight % of the amide resin and 5 to 40 weight % of the non-reactive diluent.

7. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The mixing ratio of the epoxy resin to the silicone resin is 1:0.1 to 2 by weight.

8. The solvent-free two-component epoxy coating composition according to claim 1, wherein: The mixing ratio of the above amine to the above amide resin is 1:0.01 to 2 by weight.

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