JPS642151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink composition for forming a corrosion-resistant coating that is resistant to chromic acid mixtures.

Up to now, there has been known an oxidation coloring method in which a stainless steel plate is heated to 70 to 85°C and immersed in a chromic acid mixture, and various color tones are created on the surface of the stainless steel by varying the immersion time. When partially coloring stainless steel using this method, the ink composition for forming a corrosion-resistant coating is screen printed or written with a brush to form a desired image on the stainless steel surface, and then this is added to a chromic acid mixture. However, conventionally commonly used ink compositions have low resistance to chromic acid mixtures and dissolve or peel within 1 to 2 minutes, making it difficult to form a desired image.

In order to overcome these drawbacks of conventional ink compositions, ink compositions based on thermosetting resins have been proposed, such as modified melamine resins, amino resins, epoxy resins, thermosetting phenolic resins, Those whose main component is curable acrylic resin (Japanese Patent Publication No. 11566, 1973), and those whose main components are epoxy resin or melamine resin (Japanese Patent Publication No. 11566, 1972)
41705), etc. are known.

However, although such thermosetting resins exhibit good resistance to chromic acid mixtures, it is difficult to peel off and remove unnecessary coating parts after coloring treatment, and removal by dissolution is particularly difficult. Since this is impossible, it cannot be used practically.

In order to develop an ink composition that exhibits excellent corrosion resistance against chromic acid mixtures and forms a coating that can be easily removed after coloring treatment, the present inventors
As a result of extensive research, it was discovered that the objective could be achieved by using a chlorinated organic polymer compound with a chlorine content of 20 to 75% by weight as a binder in the ink component, leading to the present invention. .

That is, the present invention provides an ink composition for forming a corrosion-resistant coating, comprising an acid-resistant inorganic filler dispersed in a solution of a chlorinated organic polymer compound having a chlorine content of 20 to 75% by weight dissolved in an organic solvent. It is.

In the present invention, it is necessary to use a chlorinated organic polymer compound having a chlorine content of 20 to 75% by weight as a binder component. If the chlorine content of this product is less than 20% by weight, sufficient resistance to the chromic acid mixture cannot be obtained, and if the chlorine content is less than 75% by weight,
If the amount is more than 1% by weight, the dehydrochlorination reaction occurs, resulting in instability and insolubility in organic solvents, so it cannot be used.

Examples of such chlorinated organic polymer compounds include polymers of chlorine-containing monomers such as vinyl chloride and vinylidene chloride, copolymers of these chlorine-containing monomers with other monomers, and polymers of chlorine-containing monomers such as vinyl chloride and vinylidene chloride. Examples include chlorinated polyolefins such as chlorinated polyethylene and chlorinated polypropylene, and chlorinated rubbers such as chloroprene and chlorinated rubber.

Next, as an organic solvent for dissolving this chlorinated organic polymer compound, an organic solvent having a boiling point of 140 to 265°C, particularly one having a boiling point of 150 to 265°C is suitable for screen printing. Examples of such organic solvents include carbitol acetate, methyl carbitol acetate, butyl carbitol acetate,
Examples include esters such as ethyl cellosolve acetate and butyl cellosolve acetate, and ketones such as cyclohexanone, diisobutyl ketone and isophorone.

In addition, as the inorganic filler, which is one of the components of the present invention, it is necessary to use an acid-resistant filler such as alumina, silica, and zirconium silicate that will not be affected by the chromic acid mixture, and titanium oxide, barium carbonate, etc. It cannot be used because it is mixed with acid mixture. The inorganic filler is added in an amount of 1 to 20 parts by weight per 100 parts by weight of the chlorinated organic polymer compound. If this amount is too large, the resistance to the chromic acid mixture will be reduced, and if this amount is less than 5 parts by weight, screen printing will cause the printed matter to break and have poor smoothness, making it impossible to put it to practical use. This inorganic filler is added to the solution of the chlorinated organic polymer compound as a fine powder that passes through 200 meshes or less, and is uniformly dispersed.

A stabilizer may be added to the ink composition of the present invention as necessary to ensure stability of the chlorinated organic polymer compound. Examples of such stabilizers include epoxy stabilizers and basic lead salt stabilizers, but epoxy stabilizers are particularly preferred. This material is usually added in an amount of 0.1 to 3 parts by weight per 100 parts by weight of the chlorinated organic polymer compound.

By the way, chlorinated organic polymer compounds are generally
Since it has the disadvantage of being hard and brittle, it is sometimes necessary to add a plasticizer to improve this disadvantage. Examples of such plasticizers include phthalate plasticizers, phosphate ester plasticizers, aliphatic dibasic acid ester plasticizers, polyester plasticizers, and epoxy plasticizers, but the ink composition of the present invention Of these, chlorinated paraffin is particularly preferred. The chlorinated paraffin is used in an amount of 5 to 30 parts by weight per 100 parts by weight of the chlorinated organic polymer compound.

In addition to these components, the ink composition of the present invention may contain commonly used auxiliary agents such as colorants, antifoaming agents, leveling agents, and lubricants, if desired. Furthermore, an insoluble fluororesin powder may be added as a lubricant for increasing the amount.

Although there are no particular restrictions on the concentration of solid components in the ink composition of the present invention, it is advantageous to adjust the concentration so that the final liquid has a viscosity of 30 to 1000 poise. If the viscosity is lower than this, it will not be possible to obtain a coating film of sufficient thickness when applied to the surface of stainless steel, and if the viscosity is too high, it will be difficult to apply and work will be difficult.

To prepare the ink composition of the present invention, predetermined amounts of an organic solvent, a chlorinated organic polymer compound, an acid-resistant inorganic filler, and other auxiliary agents are mixed and thoroughly kneaded using a triple roll.

The ink composition thus obtained is printed on a stainless steel plate by screen printing to form a desired pattern, and then dried at a temperature of 60° C. or higher to form an image coating. Next, when this is immersed in a chromic acid mixture whose temperature is adjusted to 78-80°C, the surface of the plate changes to deep purple after 5 minutes, yellow after 10 minutes, green after 18 minutes, and black after 23 minutes. Therefore, by utilizing this color change, various colored patterns can be applied to stainless steel.

After the coloring treatment, the coating remaining on the surface can be easily peeled off and removed by washing with a solvent.

In this way, the ink composition of the present invention can form a coating that can sufficiently withstand the chromic acid mixture, and unlike the case of conventional thermosetting resins, this coating can be easily peeled off. It is suitable for forming a corrosion-resistant coating during partial coloring treatment of stainless steel.

When the ink composition of the present invention is applied and the solvent is removed to form a coating, the presence of at least 65% by weight of the chlorinated organic polymer compound in the coating provides good stability, especially against chromic acid mixtures. I knew it would become something. Therefore, it is desirable to select the solids composition such that such a coating is formed.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 The following raw materials were mixed in a high-speed mixer and then kneaded in a three-roll mill to obtain an ink composition for forming a corrosion-resistant coating with a viscosity of 160 poise (measured at 25°C using a Visco Tester-0.2).

Chlorinated polyethylene/vinyl acetate/methacrylic acid copolymer (weight ratio 98:1:1) (chlorine content 67~
68% by weight (molecular weight approx. 8500) 175 parts by weight Chlorinated paraffin (chlorine content 50% by weight)
13 parts by weight Epoxy resin (Epicoat 828 # manufactured by Ciel Petrochemicals) 2 parts by weight Silicon oxide fine powder (Aerosil 200 # manufactured by Nippon Aerosil) 7 parts by weight Silicone antifoaming agent 2 parts by weight Phthalocyanine green (pigment) 1 part by weight cyclohexanone 100 parts by weight Butyl cellosolve acetate 60 parts by weight Diisobutyl ketone 40 parts Next, the surface-polished stainless steel was degreased with a 5% aqueous solution of sodium triphosphate at a liquid temperature of 60°C, washed with water, and then dried. After screen printing was performed on this stainless steel using the ink composition for coating formation obtained above, it was dried at 90° C. for 30 minutes.

Next, 240 g of chromic acid anhydride and 460 g of concentrated sulfuric acid were placed in a beaker, and pure water was added thereto to prepare a chromic acid mixture solution, which was maintained at 80° C.±2° C. in a constant temperature bath. When the above-mentioned screen-printed stainless steel plate was immersed in this chromic acid mixture, the area other than the coating area was gradually oxidized and turned dark purple-blue, and turned yellow about 10 minutes after the start of immersion.

Next, when trichlorethylene was used to dissolve the coating on the coating forming part, it was possible to dissolve and remove it in about 40 seconds.

Example 2 The following raw materials were mixed and dissolved using a high-speed mixer, and heated and defoamed to obtain an ink composition for forming a corrosion-resistant coating.

Chlorinated rubber (chlorine content 65% by weight, molecular weight approximately 12000)
120 parts by weight Chlorinated polyethylene (chlorine content 40% by weight, molecular weight approx. 6500) 50 parts by weight Epoxy resin (Epicote 828# manufactured by Ciel Petrochemicals) 30 parts by weight Silicon oxide fine powder (Aerosil 200# manufactured by Nippon Aerosil) 3 parts by weight 180 parts by weight of methyl carbitol acetate Next, the coating formation ink composition obtained above was screen printed on stainless steel that had been degreased in the same manner as in Example 1, and then heated at 110°C.
and dried for 20 minutes.

Next, when the above-mentioned screen-printed stainless steel plate was immersed in a chromic acid mixture prepared in the same manner as in Example 1, the parts other than the coating formation part were gradually oxidized and the color changed from deep purple-blue to yellow. It turned green in about 18 minutes.

Next, this was washed with water and dried, and then the coated area was gently wiped with absorbent cotton impregnated with methylene chloride, and this coat was easily removed.

Example 3 The following raw materials were kneaded using a triple roll to obtain an ink composition for forming a corrosion-resistant coating having a viscosity of about 190 poise.

Chlorinated polypropylene (chlorine content 63% by weight, molecular weight approx. 3000) 99 parts by weight Epoxy resin (phenol novolak type,
DEN438 (manufactured by Dow Chemical Company) 1 part by weight Zirconium silicate (particle size 5μ) 15 parts by weight Cellosolve acetate 60 parts by weight Xylene 50 parts by weight Next, using the ink composition for coating formation obtained as described above, Example 1 When screen printing was carried out on stainless steel in the same manner as above, and the obtained stainless steel plate was immersed in a chromic acid mixture, the parts other than the areas where the coating was formed gradually became oxidized and turned dark purple-blue in about 5 minutes after the start of immersion. Ta.

Next, when the coated portion was dissolved using methyl ethyl ketone, it was easily dissolved and removed.

Example 4 The following raw materials were kneaded using a three-roll mill to obtain an ink composition for forming a corrosion-resistant coating.

Polyvinyl chloride (vinyl chloride 97: vinyl acetate 3) 100 parts by weight Chlorinated paraffin 10 parts by weight Epoxy resin (Epicote 1001# manufactured by Ciel Petrochemicals) 2 parts by weight Silicone antifoaming agent 0.5 parts by weight Silicon oxide fine powder (Aerosil 300) #manufactured by Nippon Aerosil Co., Ltd.) 6 parts by weight Isophorone 80 parts by weight Next, screen printing was carried out using the ink composition for coating formation obtained above on stainless steel that had been degreased in the same manner as in Example 1. After 90℃
Dry for 20 minutes.

Next, put 300g of ammonium dichromate and 500g of concentrated sulfuric acid into a beaker, add pure water and stir.
Prepare a chromic acid mixture as
The temperature was maintained at 80°C±2°C. When the above-mentioned screen-printed stainless steel plate was immersed in this chromic acid mixture, the parts other than the coated areas were gradually oxidized and colored red about 25 minutes after the start of immersion.

Next, when the coated portion was dissolved using acetone, it was easily dissolved and removed.

Example 5 The following raw materials were kneaded using a three-roll mill to obtain an ink composition for forming a corrosion-resistant coating.

Chlorinated rubber CR-90 (manufactured by Asahi Denka Kogyo Co., Ltd.) (chlorine content
65% by weight or more, molecular weight approximately 60,000) 70 parts by weight Chlorinated rubber CR-5 (manufactured by Asahi Denka Kogyo Co., Ltd.) (Chlorine content
65% by weight or more, molecular weight approximately 5000) 30 parts by weight Chlorinated polyethylene (chlorine content 70% by weight, molecular weight approximately 4500) 40 parts by weight epoxy resin (Epicote 828# manufactured by Ciel Petrochemicals) 7 parts by weight silicon oxide fine powder (Aerosil) 300# manufactured by Nippon Aerosil Co., Ltd.) 9 parts by weight Silicone antifoaming agent 0.6 parts by weight Methyl carbitol acetate 150 parts by weight Next, stainless steel that had been degreased in the same manner as in Example 1 was treated with chromic acid prepared in the same manner as in Example 1. It was immersed in the mixed solution for 6 minutes to oxidize it to blue-purple. After screen printing on this stainless steel using the ink composition for coating formation obtained above.
It was dried at 110°C for 20 minutes.

Next, when the screen-printed stainless steel plate was immersed in the chromic acid mixture, oxidation progressed further in areas other than the coated areas, and the plate turned yellow-green in about 8 minutes after immersion was restarted.

Next, this was washed with water, dried, and the coated area was wiped off with absorbent cotton soaked in methylene chloride, and the coat was easily removed.

In this way, a multicolored stainless steel plate was obtained in which the coated portion was bluish-purple and the other portions were yellow-green.

Comparative Example 1 When the same treatment as in Example 1 was carried out using a normal etching resist ink (mainly consisting of petroleum resin and cyclized rubber) as an ink composition for forming a coating, after immersing stainless steel in a chromic acid mixture, The coated area was completely destroyed within 1 minute.

Comparative Example 2 The following raw materials were kneaded with three rolls and the viscosity was approx.
An ink composition for coating formation of 200 poise was obtained.

Polyvinyl butyral resin 50 parts by weight Phenol novolak resin 40 parts by weight Ethylene/vinyl acetate copolymer 20 parts by weight Silicon oxide fine powder (Aerosil 200# manufactured by Nippon Aerosil Co., Ltd.) 7 parts by weight Silicone antifoaming agent 2 parts by weight Cyanine Green 1 weight 70 parts by weight Cellosolve 20 parts by weight Isobutyl ketone 50 parts by weight Next, screen printing was performed on stainless steel that had been degreased in the same manner as in Example 1 using the ink composition for coating formation obtained above. 100℃ after
and dried for 30 minutes.

Next, when the above-mentioned screen-printed stainless steel plate was immersed in a chromic acid mixture prepared in the same manner as in Example 1, stains due to erosion appeared on the coated area about 5 minutes after the start of immersion, and became obvious after about 10 minutes. The area where the coating was formed was attacked and discolored, and the coating swelled and peeled off after about 15 minutes.

Claims (1)

[Scope of Claims] 1. An ink composition for forming a corrosion-resistant coating, comprising an acid-resistant inorganic filler dispersed in a solution of a chlorinated organic polymer compound having a chlorine content of 20 to 75% by weight dissolved in an organic solvent. 2 The chlorinated organic polymer compound with a chlorine content of 20 to 75% by weight is polyvinyl chloride, polyvinylidene chloride,
The composition according to claim 1, which is at least one selected from chlorinated polyethylene, chlorinated polypropylene, chloroprene rubber, and chlorinated rubber.