JPS6166766A - Corrosion-proofing paint - Google Patents

Abstract

PURPOSE:To obtain the titled non-toxic paint for automobiles, etc., having corrosion-proofing effect even under exposure to rain containing sea water or in a hot and humid environment, by adding a specific amount of meta-kaolin coated with magnesium oxide. CONSTITUTION:The objective paint can be prepared by compounding (A) 100 pts.(wt.) of a resin for paint with (B) 0.5-50pts. of meta-kaolin coated with magnesium oxide. The above meta-kaolin is preferably an amorphous substance prepared by heat-treating a clay mineral composed mainly of kaolinite, dickite, nacrite, metahalloycite, etc. at 600-900 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is directed to an anticorrosion paint for automobiles, building materials, outdoor structures, etc., particularly a paint that is excellent in anticorrosion in a salty environment.

(Conventional technology and problems) Automotive vehicles/parts, chemical type 2, building materials.

Painting outdoor structures, agricultural machinery, electrical appliances, etc. requires not only aesthetics but also anti-corrosion performance.

In recent years, as the need for resource conservation has increased, there has been a desire for coated products that do not deteriorate in performance over a longer period of time due to corrosion protection, etc.

In addition, the environments in which coated products are used are becoming more diverse, and they are increasingly being used in harsh environments where corrosion is likely to occur, and in this sense, the demand for anti-corrosion performance is becoming even stronger.

For example, cars that drive on roads coated with antifreeze agents (calcium chloride or rock mounds) constantly come into contact with salt water and the like. Also,
Painted parts such as aluminum sash and balconies of buildings in coastal areas are exposed to wind and rain containing seawater. As described above, painted objects are often placed in harsh environments where they are susceptible to corrosion.

Typical types of corrosion that reduce the performance of painted objects include:
When there is a scratch on a painted object, the base material in that area begins to dissolve, and at the same time, the adhesion between the paint film and the base material that is in contact with the scratch begins to decrease, causing a phenomenon in which am peels outward from the scratch over time. .

There are also the following types of corrosion: Even if there are no scratches, when the paint film comes into contact with wood, N&+ ions or C exchange ions in the water pass through the paint film and reach the base material, creating a local potential difference on the base material surface and causing the base material to elute.Anode part and the cathode part of the counter electrode are generated. Peeling of the coating film occurs at these 7 node portions and the cathode portion. Water accumulates in the gaps and causes blisters. Eventually, the paint film breaks and an aqueous solution called rust fluid flows out, which not only significantly impairs the aesthetics but also shortens the lifespan of the painted product.

Many researchers have made efforts to prevent such corrosion, and several techniques have been provided so far. The main ones are described below.

In order to prevent corrosion, methods such as increasing the thickness of the paint film by applying multiple coats of paint have been implemented. However, there were drawbacks such as an increase in the number of painting steps and an increase in the amount of paint used. In addition, in order to prevent corrosion, we focused on improving the adhesion between the base material and the coating film, and published JP-A-50-1391.
No. 29.

A method of introducing a compound forming a chelate bond at the interface between the base material and the coating film as disclosed in JP-A-52-151323, or a method of introducing a compound forming a chelate bond at the interface between the base material and the coating film as disclosed in JP-A-53-113835. A method has been implemented in which a coupling agent is interposed at the interface of the coating film. However, resins that can be chelated or coupled have selectivity, which has the drawback of restricting the selection of resin materials for coatings.

Additionally, a method of incorporating rust-preventing pigments into paints has been implemented to prevent corrosion. Among them, chromate pigments such as zinc chromate are by far the most common.When these pigments come into contact with moisture, they elute chromate ions, and their strong liquefying action turns the metal surface into an unwA state, exerting a corrosion-preventing effect. It is something to do. However, compounds containing heavy metals are toxic and lack safety.

(Problem of the present invention) The present invention solves these problems and suppresses corrosion even in environments where corrosion is likely to occur, such as being exposed to wind and rain containing seawater or being placed under high temperature and humidity. To provide an effective paint with low pollution by using non-toxic additives.

(Means and effects for solving the problems) The present invention provides a paint mainly composed of a paint resin.
This is an anti-corrosive paint characterized by containing 0.5 to 50 il of metakaolin coated with magnesium oxide based on the weight part.

The main components of the kaolin packed earth mineral are AM and Si.
, 06 (OH), ++ nH20 (nH.

O is interlayer water and usually has a composition of nwO or an integer of 1 or more. Specifically, as substances where n=o, kaolinites, Dic
There are examples of such materials as n=1 or more, ie, materials with interlayer water, such as halloysite (Halloysite).

The shape of the kaolin group clay minerals is not constant; for example, kaolinite, dietschite, and nacrite have a hexagonal plate shape, whereas metahalloysite and halloysite have a tubular, cylindrical, or spherical shape.

The kaolin group clay minerals are commonly referred to as kaolin, and are commonly referred to as Korean kaolin, Ji, Uji 7 kaolin, New Sealant kaolin, Konggang kaolin, with the name of the place of origin added before "r kaolin". It is also called furnace door kaolin.

The metakaolin of the present invention is an amorphous substance produced by metamorphosis of the above-mentioned kaolin group clay mineral when the mineral is heated,
Although it retains the structure of the mineral, it no longer returns to its original state even if it absorbs and adsorbs a large amount of water.

The heat treatment of the present invention is a step of heating camelin group clay minerals for a certain period of time to obtain metakaolin of the present invention. The heat treatment temperature of the kaolin group clay mineral is preferably within the temperature range of 600 to 900°C.

When heated within this temperature range, it dehydrates and transforms into metakaolin. Here, if the heat treatment temperature exceeds 900°C, the metakaolin will crystallize again and change into another substance, and if the heat treatment temperature is lower than 600°C, it will not be transformed into metakaolin, which is both undesirable. .

The L foot heat treatment time is not determined depending on the heat treatment temperature, but is generally from several minutes to 5.6 hours. The higher the heat treatment temperature, the shorter the heat treatment time.

Note that the longer the treatment time, the more stable metakaolin can be obtained. The atmosphere for this heat treatment is preferably air or an inert gas.

In order to be used in the paint of the present invention, this metakaolin must be coated with magnesium oxide. Therefore, in the actual process, a water-soluble magnesium compound is first deposited on the surface of a clay mineral whose main component is one kind or a mixture of two or more kinds of kaolin, such as kaolinite, halloysite, and metahalloysite. The coating method is #
A simple and practical method is to disperse kaolin in an aqueous solution of a water-soluble magnesium compound such as magnesium acid, magnesium nitrate, or magnesium halide. after that,
If the above-mentioned heat treatment is carried out at a temperature of 600 to 900"C, kaolin is converted to metakaolin 7 and at the same time magnesium is also oxidized to obtain metakaolin coated with magnesium oxide (hereinafter referred to as Mg-metakaolin). - Metakaolin is an amorphous powder with a particle size of.

Preferably, the thickness is about too-0.1 pm.

When Mg-metakaolin prepared in this way is blended into a paint, it is thought that ions in the salt water are captured in the paint film, although it is not certain, so it effectively suppresses the occurrence of corrosion such as flaking. It has the effect of

The anticorrosion paint of the present invention is a mixture containing the above paint resin and Mg-methakaolin as essential components. The appropriate amount of Mg-methakaolin to be mixed is O.S ~ 50j per 100 parts by weight of paint resin! It is a small amount and has a corrosion inhibiting effect within the range of placement. In order to obtain a better corrosion-preventing effect, it is desirable that the amount is in the range of 3 to 20 parts by weight.If the amount of Mg-metakaolin is less than 0.5 parts by weight, no corrosion inhibiting effect will be obtained, and if it exceeds 50 parts by weight. Does this mean that the aesthetic appearance of the paint film deteriorates? This is not preferable because the flexibility of the 'lJA film decreases, and although the hardness increases, the brittleness also increases.

The anticorrosion paint according to the present invention is contained in the vA resin for paints.
It is preferable that the powder of g-metakaolin is appropriately dispersed and solidified, and it is also possible to add a solvent to give it an appropriate viscosity and make it easier to paint.Furthermore, a pigment for coloring the paint, Appropriate amounts of resin preservatives, antifoaming agents, leveling agents, hardening accelerators, and plasticizers may be added.

When the anticorrosive paint according to the present invention is formed as a paint film on the surface of a painted product, it is not clear how it exhibits the effect of preventing corrosion of the base material that causes peeling of the paint film, such as blistering, but it is as follows. It can be considered.

Even if corrosive ions such as Na enter from the surface of the paint film, the Mg-methakaolin in the paint film will not absorb Na.
This is thought to be due to the fact that Na is taken in and Na does not reach the base material. 'il again! If there is a scratch on the coating, this uneven part becomes the 7 node of the corrosion battery, and the area under the coating film at the opening of the uneven part becomes the cathode. In this case, if Na is present at the cathode, OH- generated at the cathode is successively neutralized by Na+, and corrosion of the base material progresses. It is considered that the presence of Mg-metakaolin causes Na to be incorporated into the Mg-metakaolin, thereby suppressing corrosion.

The method for preparing the anticorrosive paint according to the present invention is as follows.

First, a commonly used organic paint is prepared. The organic paint preferably contains, in addition to the paint resin, pigments, additives, and a solvent to achieve a viscosity suitable for painting work.

, Meanwhile, prepare a predetermined amount of powdered Mg-metakaolin,
Mix with the above organic paint. At this time, the mixing method uses a ball mill, sand grinder, roll mill, etc.
It is necessary to mix until the g-metakaolin is sufficiently dispersed in the organic paint.

In order to make the dispersion of Mg-metakaolin more uniform, M
It is preferable to further add a solvent in an amount of 5 to 10 times the weight of g-metakaolin.

Apply the paint obtained as above to the desired base material.

After application by methods such as brushing, spraying with a spray gun, and barcoding, it is dried to form a coating film on the surface of the substrate. Even if a #'4 coated film is exposed to salt water for a long period of time, the cations in the salt water do not easily reach the base material, making it difficult for poor corrosion such as blistering to occur.

(Example) Example 1 Kaolin powder produced by New Sealant (main component: metahalloysite) 2, in which 1.43 kg of commercially available magnesium acetate (manufactured by Hanui Chemical Co., Ltd.) was dissolved in 7 volumes of distilled water in a 10 IL beaker. Add .3 kg and heat the beaker to 95℃.
The water is evaporated while the mixture is stirred with a propeller, and the kaolin powder coated with magnesium acetate (
(hereinafter referred to as Mg-kaolin powder) was obtained. The Mg-kaolin powder was crushed in a mortar and then passed through a 300 mesh sieve to be classified.

The Mg-kaolin powder passed through a 300-mesh sieve was calcined at 600 to 900°C for 2 hours in a crucible aluminum furnace at 100°C intervals to obtain the Mg-metakaolin of the present invention. 1 part carbon black to 100 parts by weight of modified alkyd resin
0 parts by weight, 7 parts by weight of Asionka, 3 parts by weight of calcium carbonate,
A predetermined amount of butyl cellosolve was charged into a sand grinder container and dispersed at 2,500 rpm for 2 hours, then 10 parts by weight of the above Ml-metakaolin was added and dispersed again using a sand grinder at 2,500 rpm for 3 hours. 1. Invention of the Invention The water-based paint was prepared.

In addition, the above commercially available water-based epoxy modified alkyd resin 100
Carbon black, zinc white, calcium carbonate, and butyl cellosolve were added in exactly the same parts by weight as above.
After dispersing with a sand grinder under exactly the same conditions as described,
Among the above Mg-metakaolin powders, 0.0.5
, 1°10.20, 30, 40, 50.60 parts by weight were added and dispersed again using a sand grinder to prepare a water-based paint.

Furthermore, each paint on the hill was diluted with water and adjusted to a viscosity suitable for painting with a spray gun, and then degreased with petroleum benzine in advance.
) Three sheets each were coated with each paint so that the dry film had a thickness of about 201 Lm.

After painting, these ° mild steel plates were held at 110 °C for 20 minutes,
Baking was performed to form a paint film. For comparison, Mg
- A coating film made of the above water-based paint resin that does not contain any metakaolin powder is degreased in advance with petroleum benzine 3
It was formed on the surface of a sheet of mild steel.

Next, cut the paint film on the surface of each of these three mild steel plates using a cutter knife to reach the base material and meet JIS-5400.
Corrosion resistance tests were conducted using the salt water fountain test method in accordance with .

The results are shown in Figures 1 and 2.

The value on the vertical axis in the figure is the maximum value of the time (SS time) until the bulge width due to corrosion reaches 6 mm around the cut. Comparative example of coating device Ik without adding Mg-metakaolin
The rusted steel plate was aged for 96 hours.

In Figure 1, all mild steel plates coated with a paint containing Mg-methakaolin obtained by heat treatment at a temperature range of 800 to 900°C have an anticorrosive effect, and among them, Mg-metakaolin obtained by heat treatment at 800°C Mild steel sheets coated with kaolin paint showed the greatest effect. In Figure 2, 0, 5 to 50
F) (R (perhundred resin) or less, an anticorrosion effect was observed at any addition amount, and the maximum anticorrosion effect was observed at l OPHH.

Example 2 Mg-kaolin powder passed through the same 300-mesh sieve as prepared in Example 1 was calcined for 2 hours in a crucible-type nichrome furnace at a temperature of 800°C to obtain Mg-metakaolin.

Next, to 100 parts by weight of water-dilutable linseed oil, 50 parts by weight of rutile titanium oxide, 80 parts by weight of calcium carbonate, 20 parts by weight of zinc white, and cobalt naphthenate (cobalt content is 6%).
) 2.2 parts by weight, roughly the above Mg-metakaolin toz
Pour the specified amount of part B into the container of the sand grinder 250
A paint containing linseed oil #M fat as a main component was prepared by dispersing for 4 hours at 0 rotations/min.

5 pcc mild steel plate (7
x150x0.8t/mm) Approximately 35# dry coating on 3 sheets
The above paint was applied to a thickness of Lm using Parney Goo. The coated mild steel plate was held at 120° C. for 20 minutes to form a dry coating film. For comparison, a coating film consisting of a paint containing no Mg-metakaolin powder and having the above-mentioned linseed oil resin as a main component was similarly formed on the surfaces of three mild steel plates.

Next, the paint films on the surfaces of these three mild steel plates were cut with a cutter knife to reach the base material, and a corrosion resistance test was conducted using a water spray test method.

The results are shown in Table 1.

Example 3 A commercially available thermosetting acrylic paint resin (trade name Almatex 782-5 manufactured by Mitsui Toatsu Chemical Co., Ltd.) and the same Mg-metakaolin powder used in Example 2 were mixed with 5 to 10 times the amount of xylene as the main component. Prepare a dispersion liquid that is uniformly dispersed in paint thinner using an emulsifying machine, and add thermosetting acrylic paint resin 1.
30 parts by weight of rutile titanium oxide Mg per part by weight of oo
- The anticorrosive paint of the present invention was prepared by mixing and kneading so as to contain 10 parts of metakaolin. - Furthermore, dilute the above paint with thinner to a viscosity suitable for painting with a spray gun! After that, 5PCC mild steel plate (7X150X0.8-t
/mm), and three coats of the above paint were applied so that the dried film had a thickness of about 30 m. After painting these mild steel plates at 160'C! , hold for 20 minutes, bake, and apply.
A TLT film was formed.

For comparison, a JJT film containing no Mg-methakaolin powder and mainly made of the above acrylic paint resin was formed on three other 5PCC mild steel plates that had been degreased with petroleum benzine.

Next, a corrosion resistance test of the paint film on the surface of these mild steel plates was conducted in the same manner as in Example 1.

The results are shown in Table 1.

Example 4 Nitrocellulose [manufactured by Ohira Chemical Products Co., Ltd.] 80 parts by weight, non-oxidized alkyd resin [Betucosol 1308 manufactured by Dainippon Ink Chemicals Co., Ltd.] 20 parts by weight, rutile titanium oxide 10 parts by weight, MIBK25 ([ 1 part and further 10 parts by weight of Mg-metakaolin, the same as that used in Example 2, were charged in a predetermined amount into a sand glider container.
The mixture was dispersed at rotation/minute for 4 hours to obtain the coating material of the present invention.

The same mild steel plate as used in Example 1 was coated with a bar coater. Furthermore, for comparison, the above steel plate was coated with a paint containing no Mg-methakaolin and containing the above resin as a main component. after that.

The above steel plate was held at 60℃ for 10 minutes and dried, resulting in a film thickness of 2.
A coated steel plate with a thickness of 5 μm was obtained. Corrosion resistance tests were conducted on each of the three coated steel plates using the same salt spray test method as in Example 1.

The results are shown in Table 1.

Example 5 120g of modified epoxy resin was milled in a ball mill to 0.1 to 0.
．． After grinding to a particle size of 5 pLm, 1
5 gr was added, and the reaction was carried out in a zero atmosphere of N2 gas. Next, 7.2 gr of acrylic acid was added and reacted at a temperature of 8Q-120°C to adjust the acid value to 1-2.

100 gr of blocked tolylene diincyanate was added to this modified epoxy resin, and the mixture was stirred while keeping warm at 80"C to obtain a resin for cathodic deposition type electrodeposition paint.

To 111,100 parts by weight of the wood, 10 parts by weight of titanium oxide as an extender pigment was added, ground and mixed using a sand grinder in a conventional manner, and 1 part of Mg-metakaolin powder, which was the same as that used in Example 2, was added.

After going through the dispersion process again with a sand grinder at 2500 rotations/rotation time, distilled ion exchange water was added so that the solid content was 15%, and triethylamine was added to adjust the pH to 8 to 9: JJffl, - Polar precipitation type It was used as an electrodeposition paint.

Three sheets degreased with T-320 thinner and petroleum benzine (
7) SPCC soft m plate (70X150X0.8t/mm)
The coating was applied by cathodic electrodeposition under the conditions shown in Table 2 to a thickness of 2.
Electrodeposition coating was applied to approximately 5 reeds. For comparison, a paint containing the above-mentioned resin as a main component and containing no Mg-metal phosphorus was coated with MLIj in the same manner as above.

After drying the electrode coated plate at 180°C for 20 minutes, Example 1
Corrosion resistance tests were conducted using the same salt spray test method. The results are shown in Table 1.

Example 6 Alkyd resin 10 dissolved in isopropyl alcohol
The same Mg-metakana 9 used in Example 2 was added to 0 parts by weight.
10 parts by weight of Mg-methakaolin was added, and the particle size of Mg-metakaolin was reduced to 0.5 ALm using a sand grinder and a ball mill.
After dispersing the mixture until the particle size was as follows, 10 parts by weight of calcium carbonate, which is a white pigment, was added, and the mixture was further mixed and ground using a sand grinder until the particle size of the calcium carbonate was 3 μm or less. Add ion-exchanged water to the above alkyd resin containing Mg-metakaolin and white pigment, adjust the solid content to 15ffi weight percent, form an emulsion with a high-speed stirrer, and use an anodic deposition type electrode R91.
It was paid as a fee.

In addition, in order to prevent the resin from gelling when adding dedicated ion exchange water, the pH was maintained at 8 with triethylamine: JJg! Shita. In addition, an antifoaming agent was also added at the same time to avoid the inclusion of air bubbles during TA adjustment.

SPCC mild steel plate (70X
150 x 0.8 t/mm) under the conditions shown in Table 3 to prepare three coated plates with a coating thickness of about 25 pm. For comparison, a paint containing no Mg-metakaolin and containing the above resin as a main component was applied by electrodeposition in the same manner as above.

Table 3 Electrodeposition conditions The three coated plates prepared above were dried at 180°C for 20 minutes to prepare samples for the salt spray test, and the corrosion resistance was tested using the same method as the salt spray test method described in Example 1. carried out. The results are shown in Table 1.

Example 7 Blocked isocyanate cured phase polyester resin [trade name: Finedic M-81, manufactured by Dainippon Ink Chemical Co., Ltd.
05] 80 parts by weight and the same Mg-
10ffi of metakaolin was mixed and kneaded twice at a temperature of 100° C. or less using a heating roller to obtain a main ingredient. Main agent 90) [(Blocked isocyanate for placing part)
Inil Co., Ltd., product name: Fulleran UI] 17 parts by weight, bisphenol type epoxy resin [Dainichi Ink Chemical Co., Ltd., product name: Epicron 2050 (epoxy equivalent: 85
0) Add 13 parts by weight of a curing accelerator [10.2 parts by weight of dibutyltin dilaurate, 0.5 parts of a rolling agent [trade name Niaclonal 4F, manufactured by BASF], and 1 part of 33ffi of rutile titanium oxide, and heat to a temperature of 100°C or less again. Kneading was performed using heated rollers. After cooling the mixed material and pulverizing it with a pulverizer [Sanko Rikagaku Kogyo Yosei Sunko Mill], 15
The same mild steel plate as that used in Example 1, which was cleaned with petroleum benzene, was used as a powder coating for the material that passed through the mesh sieve. ! After f& coating, baking was performed at 180° C. for 30 minutes to obtain a coated steel plate with a film thickness of 35 gm. Same as in Example 1 for the three coated steel plates.

A corrosion resistance test was conducted using the salt water spray test method. The results are shown in Table 1.

Example 8 In the same manner as in Example 1, using kaolin powder (main component: kaolinite) produced in Japan instead of kaolin powder produced in New Sealant, Mg- Kaolin powder was obtained.

This Mg-kaolin powder was heat treated at 800°C for 2 hours,
Mg-metakaolin was obtained.

Next, commercially available water-based epoxy modified alkyd resin 100 weight 9
parts, carbon black and zinc.

Calcium carbonate, butyl cellosolve, Mf-metakaolin, etc. were mixed and dispersed in the same proportions and in the same manner as in Example 2 to prepare a water-based paint of the present invention. Furthermore, this water-based paint was subjected to an anti-corrosion test in exactly the same manner as in Example 2. For comparison, a test was also conducted on a coating film containing the above-mentioned resin as a main component and containing no lMg-metakaolin.

The results are shown in Table 1.

(Effects of the Invention) As described above, the paint of the present invention has the effect of preventing corrosion caused by salt water, etc., and is highly useful in various industrial fields of application.

[Brief explanation of drawings]

Figure wIJ1 is a graph showing the relationship between the firing temperature and anticorrosion effect of metakaolin used in the paint of the present invention. FIG. 2 is a graph showing the relationship between the amount of metakaolin added and the anticorrosion effect. Applicant Toyota Central Research Institute Co., Ltd. Representative Patent Attorney Asa Kato Road Figure 1 Mirror C) Masutomo (0C) Figure 2 Figure 1 Ka-l (PHR)

Claims (2)

[Claims] (1) An anticorrosive paint characterized by containing 0.5 to 50 parts by weight of metakaolin for coating magnesium oxide with respect to 100 parts by weight of paint resin. (2) The metakaolin is a clay mineral whose main component is one or a mixture of two or more of kaolinite, dickite, nacrite, and metahalloysite.
The anticorrosive paint according to claim 1, which is an amorphous material heat-treated at a temperature of .degree.