KR102480721B1 - Inside coating composition for drum with high corrosion resistance - Google Patents

Abstract

The present invention is a highly corrosion-resistant inner paint for drums that can replace existing imported products, and aims to provide two types of paint: Epoxy-Phenolic (condensation polymerization of phenol in epoxy) and Pure Phenolic (epoxy-free method). .
The present invention for achieving the above object is a paint composition for the inner surface of a drum comprising a butyl resole resin, a pigment, an auxiliary agent and a solvent,
The butyl resol resin is formaldehyde methylphenol and 56 to 64 parts by weight of a polymer of phenol, 0.5 to 2.5 parts by weight of phenol, 0.1 to 0.5 parts by weight of 2-methylphenol, and 0.1 to 0.5 parts by weight of formaldehyde Solvent Butyl Alcohol / Ethyl alcohol 32 to 44 parts by weight It is a modified butyl resole resin synthesized by condensation polymerization under weight,
The pigment is characterized in that P / B 0.3 ~ 0.8 as an iron pigment.
The present invention also relates to an epoxy-phenolic resin synthesized by condensation polymerization of 60 to 80 parts by weight of epoxy containing 1600 to 2300 epoxy groups in one molecule of epoxy and 20 to 40 parts by weight of allyl phenol in the presence of a phosphoric acid-based acid catalyst. Characterized in that the paint composition for the inner surface of the drum further comprises.

Description

Inside coating composition for drum with high corrosion resistance}

The present invention relates to an inner paint composition for drums having high corrosion resistance, and more particularly, to an inner paint composition for drums that has excellent properties in pigment settling and wettability, popping properties, etc. and can replace imported products.

Can consists of a 2PC CAN composed of a body and a lid (Easy Open End, hereinafter referred to as E.O.E) and a 3PC CAN composed of a body, upper plate and lower plate according to the molding of a metal tube. Depending on the type of contents, it is used as a food packaging container. It is divided into food tubes and other packaging containers, such as miscellaneous tubes.

The drum belonging to the miscellaneous pipe is a kind of 3PC CAN type, and is vulnerable to corrosion by using Cold Rolled Steel Sheet (CR), which is not plated, and is bulky, so it is spray-painted. The inner surface of the drum is unpainted if there is no corrosiveness due to the contents, but if there is corrosiveness, it is painted, and epoxy-phenolic type is mainly used. Epoxy-phenolic paints have the advantage of excellent adhesion and flexible coating to withstand external impact (Dent), but have the disadvantage that the coating cannot withstand strong corrosive contents and peels off. In particular, when the content contains many highly corrosive chemicals, polar (acidic or basic) substances, neutralizers (amines or acids) and emulsifiers, a high level of corrosion resistance is required for the inner coating.

In addition, since drum cans are manufactured by separately spray-painting the body and upper and lower plates during molding and then bonding them together, they are sensitive to surface contamination that occurs during the molding process. In the case of the body, since the painted surface passes through the drying furnace in a vertical state after painting, flowability prevention is required, and the coating film must not be deformed by external impact, and the material's rust prevention for various contents and the corrosion resistance of the coating film must be required.

Accordingly, the physical properties required for the inner paint of the drum are good wetting for the material (CR steel plate), good flowability (Sagging) and leveling in Spray Coating (especially at the body welding part), and bell Atomizer (Nodson) When electrostatic spray painting, the electrical resistance of the paint must meet the standard of 0.08 ~ 0.8㏁, and repainting must be possible. In addition, there should be no peeling or cracking of the inner coating film from external impact (Dent), and the rust prevention and corrosion resistance of the contents must be excellent. In addition, raw materials used must comply with FDA 21 CFR 175.300 regulations that can be used for food and medicine.

In Korea, Gangnam Jevisco paint of epoxy-phenol type is mainly used. This paint is Epoxy-Phenoilic Gray Lining, which is cured with phenolic resin with excellent corrosion resistance to epoxy resin with excellent adhesion and flexibility, added with pigment (TiO2) for thick film coating and rust prevention, and adjusted to gray color for concealment. However, the paint film does not withstand highly corrosive chemicals, amine neutralized water-based paints, surfactants, etc., and the coating film is peeled off and the material is corroded. 800L (Pure Phenolic Brown Color Lining) is used.

The purpose of the present invention is to develop a drum inner paint having high corrosion resistance corresponding to the Resco imported product. In the present invention, Epoxy-Phenolic (condensation polymerization of phenol in epoxy) and Pure Phenolic (epoxy-free method) It is intended to provide a type of paint.

The present invention for achieving the above object is a paint composition for the inner surface of a drum comprising a butyl resole resin, a pigment, an auxiliary agent and a solvent,

The butyl resol resin is formaldehyde methylphenol and 56 to 64 parts by weight of a polymer of phenol, 0.5 to 2.5 parts by weight of phenol, 0.1 to 0.5 parts by weight of 2-methylphenol, and 0.1 to 0.5 parts by weight of formaldehyde Solvent Butyl Alcohol / Ethyl alcohol 32 to 44 parts by weight It is a modified butyl resole resin synthesized by condensation polymerization under weight,

The pigment is characterized in that P / B 0.3 ~ 0.8 as an iron pigment.

The present invention also relates to an epoxy-phenolic resin synthesized by condensation polymerization of 60 to 80 parts by weight of epoxy containing 1600 to 2300 epoxy groups in one molecule of epoxy and 20 to 40 parts by weight of allyl phenol in the presence of a phosphoric acid-based acid catalyst. Characterized in that the paint composition for the inner surface of the drum further comprises.

Among the auxiliaries included in each of the above compositions, 1 to 5% by weight of at least one of Highly Beneficiated Smectite Clay, Hectorite Clay, Hydrophilic Silica, Hydrophobic Silica, Mixed silica oxide, Acrylate Resin, Acrylic Flow Modifier, Poly(acrylic acid) as a viscosity modifier Viscosity can be adjusted by using part (based on solid content).

In addition, 0.05 to 1 part by weight (based on solid content) of at least one of Ethylated Propoxylated Content Alcohol, Polyether Acetate Copolymer, Polyether Siloxane Copolymer, and Polydimethylsiloxane may be used as a surface conditioning agent.

It is revealed that other solvents and the like can be appropriately selected and used from existing known components.

According to the present invention, it is possible to meet the demand for contents with high corrosion resistance that cannot be endured with the existing Epoxy-Phenolic type paint, thereby significantly increasing the range of contents that can be packed in drums and contributing greatly to the revitalization of the drum manufacturing industry. .

Hereinafter, the present invention will be described in more detail based on examples. However, the scope of the present invention is not limited by the examples.

The present inventors analyzed and compared the existing domestic paint and imported paint RESCO 500L, 800L (Universal Chemicals & Coating Inc.) to determine the strengths and weaknesses, and then prepared standards for the developed paint.

As a result of the basic physical property test on the existing paint as described above, the contents that can be used as our existing paint are limited, and it is necessary to develop a pure phenolic type paint to satisfy the physical properties of Sample 3 (RESCO 800L) in use.

In order to achieve the above objectives, suitable resins and pigments were selected to secure physical properties comparable to those of competitors.

The resin was selected by using only resin and solvent to form a coating film to check processability and impact, and then, solvent and pigment were used for the selected resin to confirm the most appropriate corrosion resistance and impact resistance. In addition, after selecting the resin and pigment, a selection test was conducted to secure the storability and painting workability of the paint.

1. Selecting the right resin

(1) Selection of Epoxy-Phenolic Resin

Example 1 above is an epoxy-phenol resin synthesized by condensation polymerization of 60 to 80 parts by weight of epoxy containing 1600 to 2300 epoxy groups in one molecule of epoxy and 20 to 40 parts by weight of allyl phenol under a phosphoric acid-based acid catalyst.

Examples 2, 3, and 4 are the same as Example 1 except that Cresol (Example 2) or Butyl modified Cresol (Example 3) or Xylenol (Example 4) was used instead of allyl phenol.

As a result of forming a coating film with the above 4 types of resins and undergoing corrosion resistance and impact resistance tests, most of the epoxy-phenol resins had good impact resistance but lacked corrosion resistance, and Example 1 was the best.

(2) Selection of Phenolic Resin

Example 3 is formaldehyde methylphenol and a polymer of phenol (CAS No. 9039-25-2) 56 to 64 parts by weight, Phenol (CAS No. 108-95-2) 0.5 to 2.5 parts by weight, 2-methylphenol (CAS No. 95-48-7) 0.1~0.5 parts by weight, Formaldehyde (CAS No. 50-00-0) 0.1~0.5 parts by weight Butyl Alcohol/Ethyl alcohol (1:1) Synthesized by condensation polymerization under 32~44 parts by weight It is a modified butyl resole resin.

Phenolic resin has excellent corrosion resistance, but is weak against impact, and Example 3 is most suitable because it supplements impact resistance in addition to corrosion resistance.

(3) Pigment & P/B Selection

Iron pigment is the best, and Example 3 was optimal in terms of viscosity and FDA approved price. The lower the P/B, the better the corrosion resistance, but the higher the thick film coating and impact resistance, the better.

2. Securing painting workability

(1) Electrical resistance value

The paint on the inside of the drum follows the Bell Atomizer (Nodson) electrostatic spray coating method. In order to achieve smooth electrostatic spray painting, the electrical resistance value of the paint should be 0.08 ~ 0.8㏁ to improve the material arrival efficiency of the paint. This is related to the polarity of the paint component, and the higher the polarity, the higher the electrical conductivity and the lower the resistance. Epoxy-Phenolic Type resin itself has an electrical resistance value of 0.23, which conforms to the standard, but proper mixing of polar solvents and non-polar solvents prevents layer separation and gelation, and can have suitable electrical resistance values. However, in the case of the Pure Phenolic Type, the polarity of the resin itself is high, making it difficult to meet the standard. This is the same as Resco800L, a paint from Universal Chemical.

(2) pigment sedimentation

Epoxy-Phenolic Type Resco 500L uses iron sulfur, so pigment sedimentation is very fast. Drum manufacturers paint after stirring every time they use a 20L container. On the other hand, the epoxy-phenol type paint according to the present invention of the same type has little pigment sedimentation, so it can be stably used in drum containers. This is to secure excellent physical properties by selecting an appropriate P / B value and auxiliary using ferrous pigments.

In addition, the pure phenolic type paint according to the present invention has a low viscosity of the resin itself, so pigment sedimentation is very fast, especially in iron-red pigments. (On the other hand, iron-red pigments have the best corrosion resistance). To improve this, As a result of selecting and applying the dispersant, thickener, and antisettling agent, excellent physical properties were secured.

(3) Comparison of painting workability

As a result of checking the painting workability, it was confirmed that our newly developed paint was superior to the competitor's paint in terms of pigment settling, wettability, and popping.

[Final Example]

In order to achieve the purpose of the invention of this paint, the Epoxy-Phenolic Type uses Epoxy-Phenol/pigment/catalyst/solvent/additive, and the Pure Phenolic Type uses Phenol resin/pigment/solvent/thickener. #4 viscosity 80-100 seconds, solid content 47-51%) and pure phenolic type paint (Podcup #4 viscosity 40-60 seconds, solid content 47-51%) were prepared.

The paint is the main resin ① [an epoxy-phenol resin synthesized by condensation polymerization of 60 to 80 parts by weight of epoxy containing 1600 to 2300 epoxy groups in one molecule of epoxy and 20 to 40 parts by weight of allyl phenol under a phosphoric acid-based acid catalyst] Or ② [formaldehyde methylphenol and polymer of phenol (CAS No. 9039-25-2) 56 to 64 parts by weight, Phenol (CAS No. 108-95-2) 0.5 to 2.5 parts by weight, 2-methylphenol (CAS No. 95-48-7) 0.1~0.5 parts by weight, Formaldehyde (CAS No. 50-00-0) 0.1~0.5 parts by weight Butyl Alcohol/Ethyl alcohol (1:1) Synthesized by condensation polymerization under 32~44 parts by weight After stirring the pigment ③ or ④ in [modified butyl resol resin], a viscosity modifier and a dispersing agent are added and dispersed to prepare a dispersion with a particle size of 20 μm or less. After that, a paint is prepared by adjusting the appropriate viscosity using a solvent.

[Evaluation of coating performance]

After preparing the paint by the method of the above example, in order to compare and evaluate the performance of the paint film, 13 g / m ² was applied to a 7X15cm CR steel plate with a bar coater, and the Epoxy-Phenolic Type was changed to 220 using an automatic discharge oven (ATO-101). At ℃ for 10 minutes, Pure Phenolic Type was dried at 185 ℃ for 10 minutes.

For the specimens obtained by the above method, the coating film properties required for the following drum inner paint were compared and evaluated according to the test method.

(1) Coating appearance (determined visually)

Observe the appearance of the coating film and compare and evaluate its smoothness, clarity, presence of defects such as pinholes, etc.

◎: Excellent, ○: Excellent, △: Normal, X: Poor

(2) impact resistance

Evaluate under the condition of 1,000g × 50cm using a Dupont type impact tester.

◎: Excellent, ○: Excellent, △: Normal, X: Poor

(3) pencil hardness

Comparative evaluation was carried out by the coating film breaking method using a pencil from Mitsubishi Unisha Co., Ltd.

(4) Adhesion (Cross Cut Test)

After making 100 1mm × 1mm square shapes using a cutter blade, a peel test is performed with 3M #610 tape, and the remaining number is measured and evaluated.

(5) solvent resistance

Solvent resistance is comparatively evaluated as the number of round trips at the point at which the coating film starts to peel off while rubbing the coating film with a constant force after 16 layers of medical gauze is coated with methyl ethyl ketone (MEK).

(6) ALTEK Mobility

Place the specimen on the mobility tester (R1 Type) of ALTEK (USA), and compare and evaluate the frictional resistance (digital value) by pulling the weight at a constant speed while placing the weight with three balls on the ground surface on the specimen. .

(7) Storage test

Cut the painted plate on the CR steel plate in the shape of an X, prepare a specimen that impacts the coating film using a Dupont impactor, prepare the chemical products necessary for checking storage stability in a 1L container, half of it is immersed, and the other half is sealed with the steam part and sealed for 60 Put it in a thermostat at ℃ and check the peeling state of the coating every day.

Contents : Amine neutralization type water-based paint (Jevisco KC-8338-043), LG Glycerin, GEQ 100 (Cationic Surfactant), Resorcinol, Kukdo 153 hardener

(8) Popping Test

After forming a coating film using a BYK-Gardner 0810 Sagging Tester, dry at 185 ° C for 2 minutes to visually check the boiling properties of the paint.

◎: Excellent, ○: Excellent, △: Normal, X: Poor

[Results of performance evaluation of coating film]

Through this test, it can be seen that the coating film impact resistance of Example 3 of the same type is superior to that of Example 5.

As a result of the comparison of painting workability, the boilability of Example 3 of the same type was superior to that of Example 5, and the wettability of the coating film of Examples 1, 2, and 3 was superior to Example 4. Through the above experiment, it can be seen that the painting workability of Examples 1, 2 and 3 is superior to that of Examples 4 and 5, which are imported paints.

As a result of the storage test for glycerin, all examples show excellent storage stability. However, the coating workability of Example 2 is superior to Example 4, and the impact resistance of Example 3 is superior to Example 5. Also, in terms of cost, Examples 2 and 3 are superior.

As a result of the storage test for the surfactant, all examples show excellent storage stability. However, the coating workability of Example 2 is superior to Example 4, and the impact resistance of Example 3 is superior to Example 5. Also, in terms of cost, Examples 2 and 3 are superior.

As a result of the storage test for the amine neutralization type paint (2PC water-soluble inner paint KC-8338-043 of Gangnam Jevisco), in the case of the Epoxy-Phenol system (Examples 1, 2, and 4), the coating film peeling occurs, but the Pure Phenolic system (Examples 3 and 5) show excellent storability. However, in the case of Example 5, it can be seen that the impact resistance is insufficient compared to Example 3 because peeling occurs at the impact area.

As a result of the storage immersion test for Resorcinol, a raw material for pharmaceuticals, the Epoxy-Phenol system (Examples 1, 2, and 4) exhibits a peeling phenomenon, but the Pure Phenolic system (Examples 3 and 5) exhibits excellent storage stability. However, Example 3 is superior to Example 5 in terms of impact resistance, and Example 3 is also superior in terms of cost.

As a result of the storage test of KMH-151 of Kukdo Chemical's phenalkamine modified type, in the case of Epoxy-Phenol system (Examples 1, 2, and 4), coating film peeling occurred, but in the case of Pure Phenolic system (Example 3, 5) It exhibits excellent storability. However, Example 3 is superior to Example 5 in terms of impact resistance, and Example 3 is also superior in terms of cost.

As a result of confirming the physical properties, workability, and storability of the coating film through the above experiments, the painting workability is superior to that of imported paints, and the storability has properties equal to or better than those of the same type of paint. In addition, compared to imported paints, domestic paints are advantageous in terms of price and have excellent physical properties, so they can be sufficiently substituted.

[Conclusion on coating performance evaluation]

Our company's Epoxy-Phenolic Type Gray Lining is mainly used domestically as drum inner paint, but the paint film cannot withstand strong corrosive contents and peels off. In particular, if the content is a highly corrosive chemical product that contains many polar groups (acidic or basic), neutralizers (amines or acids) and emulsifiers, RESCO 500L (Epoxy-Phenolic Buff Color Lining) and RESCO 800L (Pure Phenolic Lining) from UNICHEM Brown Color Lining) is used.

The present invention was simultaneously developed in two types, Epoxy-Phenolic and Pure Phenolic, for the purpose of developing a drum inner paint with high corrosion resistance corresponding to UNICHEM's RESCO series products. For Epoxy-Phenolic, Epoxy-Phenol Resin with precondensation of Epoxy and allyl phenol was used, and for Pure Phenolic, Modified Cresol Resin was used, and Koch Iron Oxide Red, which has the highest corrosion resistance, was used for the pigment. Polar and non-polar solvents were adjusted to balance electrical resistance and solvent power, and dispersants and surface conditioners were introduced to improve workability.

Epoxy-Phenolic Type, the final product according to the present invention, has improved corrosion resistance compared to the existing products, showing the same level as imported UNICEM RESCO 500L, and improved flowability through solvent composition adjustment, so it was highly evaluated in terms of workability.

In addition, Pure Phenolic Type has high corrosion resistance, but Gangnam Jevisco did not have the same type of paint, and through this development, the final product was secured. It has the same level of corrosion resistance as the imported Unichem RESCO 800L of the same type, and in particular, it can solve the problems of popping and dent, which are the disadvantages of Pure Phenolic, to gain a competitive edge in quality.

Claims (4)

A paint composition for the inner surface of a drum comprising a butyl resole resin, a pigment, an auxiliary agent and a solvent,
The butyl resol resin is formaldehyde methylphenol and 56 to 64 parts by weight of a polymer of phenol, 0.5 to 2.5 parts by weight of phenol, 0.1 to 0.5 parts by weight of 2-methylphenol, and 0.1 to 0.5 parts by weight of formaldehyde Solvent Butyl Alcohol / Ethyl alcohol 32 to 44 parts by weight It is a modified butyl resole resin synthesized by condensation polymerization under weight,
The pigment is an iron pigment and a paint composition for the inner surface of the drum, characterized in that P / B 0.3 ~ 0.8. According to claim 1,
An epoxy-phenolic resin synthesized by condensation polymerization of 60 to 80 parts by weight of epoxy containing 1600 to 2300 epoxy groups in one molecule of epoxy and 20 to 40 parts by weight of allyl phenol under a phosphoric acid catalyst. A paint composition for the inner surface of a drum. According to claim 1 or 2,
As a viscosity modifier for the paint
Drum characterized by using 1 to 5 parts by weight (based on solid content) of at least one of Highly Beneficiated Smectite Clay, Hectorite Clay, Hydrophilic Silica, Hydrophobic Silica, Mixed silica oxide, Acrylate Resin, Acrylic Flow Modifier, Poly (acrylic acid) Paint composition for interior use. According to claim 1 or 2,
As a surface conditioner for the paint
Ethylated Propoxylated Content Alcohol, Polyether Acetate Copolymer, Polyether Siloxane Copolymer, Polydimethylsiloxane of at least one of 0.05 to 1 parts by weight (based on solid content) Characterized in that the use of a paint composition for the inner surface of the drum.