JPS6036228B2 - Heat resistant corrosion protection coating material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-resistant anticorrosive coating material used to prevent corrosion of steel pipe joints, plants, high-temperature equipment, etc.

Conventionally, antirust paints and plastic anticorrosion tapes have been mainly used to prevent rust from forming on metal structures.

However, in the case of anti-rust paints, the paint film shrinks and hardens over time and loses its elasticity, cracks occur in the film due to aging, and is damaged by external impact, resulting in moisture and air. could easily touch metal surfaces and cause rust. In addition, in the case of plastic anti-corrosion tape, anti-corrosion and
Although it has excellent rust prevention effects, the tape itself is quite hard, making it difficult to apply to irregularly shaped parts such as steel pipe connections. Therefore, attempts have been made to use a permanently adhesive plastic tape containing vetrolatam as a main component for the above-mentioned irregularly shaped portions.

However, for applications where this type of tape is paste-like and can be smoothed by hand, the molecular weight of the polymer must be suppressed to around several hundred, and in this case, the sagging resistance and heat resistance at high temperatures are insufficient. When the temperature exceeds the melting point of Betrolatum, the base-like substance becomes completely liquid and drips from the wrapped steel pipe, polluting the area around the bottom and causing the anti-corrosion layer on the surface of the steel pipe to fade, significantly reducing its anti-corrosion properties. There were drawbacks. Moreover,
When exposed to high temperatures of 130oC or higher for a long period of time, it carbonized and could not perform its anticorrosion function at all. The inventors
In view of the above circumstances, as a result of intensive study to obtain a material that has good weatherability and resistance as well as sagging resistance and heat resistance at high temperatures, and exhibits improved anti-corrosion performance compared to the conventional materials mentioned above, we have developed this material. We found that a low molecular weight acrylic copolymer is suitable for this purpose, and that heat resistance and durability are further improved by providing an epoxy resin composition layer on the layer formed from this copolymer. This led to the completion of this invention.

That is, this invention is based on the following general formula; (wherein, R is hydrogen or a methyl group, and R2 is an alkyl group having 2 to 14 carbon atoms.

) Filler 1 to 3 to 100 parts by weight of an acrylic low molecular weight copolymer mainly composed of an unsaturated monomer represented by
A heat-resistant anticorrosive coating comprising an inner layer forming composition containing 0 parts by weight of 0.0 parts by weight and/or 0.2 to 20 parts by weight of a thixotropic agent, and an outer layer forming composition containing an epoxy resin and a curing agent thereof. It is related to materials.

In general, acrylic high molecular weight copolymers are often used as pressure-sensitive adhesives because of their excellent heat resistance and film resistance, but their viscosity is too high and they cannot form a paste-like film. It also has poor workability when smoothing by hand, and cannot be used as corrosion protection.

However, as in the present invention, when an acrylic low molecular weight copolymer is used and a filler or thixotropic agent is used to moderate the viscosity or to impart chicken-tropic properties, the acrylic A corrosion-preventing composition can be obtained that has excellent workability in smoothing irregularly shaped parts without impairing the heat resistance and weather resistance of the polymer. It was found to be excellent in terms of quality and was released.
In addition, if the above-mentioned anticorrosion composition is applied to the surface of a steel pipe to form an inner layer, and then an epoxy resin composition layer is further provided on top of the inner layer, since this is a thermosetting resin, it will not work at room temperature. While it does not cause damage when handled, it hardens at room temperature or under heating to form a surface layer with good heat resistance, which further improves the heat resistance and durability of the entire coating layer. It also has the function of preventing the inner layer from dripping at high temperatures, and it was discovered that the inner layer itself has excellent high-temperature properties and that good results can be obtained due to the drooping resistance at high temperatures. . As described above, the heat-resistant anti-corrosion coating material of the present invention can be easily used for hand conditioning work at room temperature, can prevent dripping at high temperatures, and has excellent heat resistance and weather resistance. Therefore, it can be applied to various irregularly shaped parts such as steel pipe connections, and places where the surface temperature of steel pipes and atmospheric temperature are high, which was difficult to apply with conventional betarolatum anticorrosion tape, such as blast furnace piping and piping inside ships, as well as petroleum, It can be widely applied to corrosion prevention in various plants such as electric power, construction, and chemical plants.

The acrylic low molecular weight copolymer in the composition for forming an inner layer of the present invention contains the unsaturated monomer represented by the general formula m as a main component, and is copolymerizable with the above monomer as necessary. It can be obtained by using other unsaturated monomers in combination and copolymerizing two or more of them in the presence of a polymerization initiator and a chain transfer agent.

The unsaturated monomer represented by the general formula (1} used here has an alkyl group (R2 in the formula) having 2 to 1 carbon atoms.
The reason why the number of carbon atoms in the alkyl group is limited as described above is that when the number of carbon atoms is 1, that is, when it is a methyl group, the anticorrosion layer becomes hard and the adhesive property is increased. On the other hand, if the number of carbon atoms exceeds 14, the adhesion to the adherend becomes poor.

The alkyl group consisting of 2 to 14 carbon atoms may be branched or unbranched, and specific examples include ethyl, n-butyl, isobutyl, 1-ethylpropyl, 1-
Examples include methylbentyl, 2-methylbentyl, 3-methylbentyl, 1-ethylbutyl, 2-ethylbutyl, 2-ethylhexyl, isooctyl, 3,5,5-trimethylhexyl, decyl, dodecyl, and the like.

Other unsaturated monomers copolymerizable with the above unsaturated monomers include alkyl (meth)acrylates other than the above general formulas, such as methyl (meth)acrylate and octadecyl (meth)acrylate. In addition, vinyl esters such as vinyl acetate, vinyl pyridine, vinyl ethers, acrylic acid, methacrylic acid, maleic acid, acrylonitrile, methacrylonitrile, methylene glutaronitrile, 2
-Hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, N/N-dimethylaminoethyl (meth)acrylate, rt-butylaminoethyl (meth)acrylate, N-methylol acrylamide, acryltamide, methacryl A wide variety of ethylenically unsaturated monomers are included, such as amide, glycidyl (meth)acrylate, butadiene, cyclohexyl acrylate, 8-ethoxy acrylate, sulfoacrylate, and fluoroalkylacrylate.

Particularly preferred among these ethylenically unsaturated monomers are acrylic acid, methacrylic acid, maleic acid,
Can react with the epoxy resin or its curing agent in the composition for forming the outer layer, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)Z acrylate, N-methylol acrylamide, and glycidine (meth)acrylate. carboxyl group, hydroxyl group, epoxy group,
It has a functional group such as an amino group in its molecule.

The low molecular weight acrylic copolymer containing such a monomer as a copolymerization component can be reacted with the epoxy resin or its curing agent in the outer layer between the inner layer formed from the copolymer and the outer layer provided thereon. As a result of this reaction, the interface between the inner and outer layers becomes more delicate and the infiltration of oxygen and moisture from the outside is completely cut off, resulting in even better results in anticorrosion performance. The type and proportion of these other unsaturated monomers may be appropriately determined depending on the purpose of use of the heat-resistant anticorrosive composition, but the If the proportion exceeds 5% by weight, heat resistance, weather resistance, durable adhesion, etc. tend to be impaired.
It should be kept at most 50% by weight or less.

As the polymerization initiator, any commonly used polymerization initiators can be used, such as penzoyl/gu-oxide, lauroyl-g-oxide, methyl ethyl ketone/g-oxide, cumene hydro/g-oxide, Q.
Examples include Q'-isobisisobutyronitrile.

Usually 0.05 to 2 parts by weight per 100 parts by weight of unsaturated monomer
It may be used in the proportion of parts by weight, but if it is desired to control the molecular weight of the copolymer to a low value with this polymerization initiator, a larger amount can be used. In addition, as a chain transfer agent, any compound having a large ability to transfer a polymer chain during polymerization may be used. Specific examples include carbon tetrachloride, carbon tetrabromide, acetic acid for trichloride, 2-mercabutylene Examples include ethanol, butyl mercaptan, and lauryl mercaptan.

These chain transfer agents are usually used in a ratio of 0.1 to 15 parts by weight per 10 parts by weight of the unsaturated monomer, but by changing this amount, the molecular weight of the low molecular weight copolymer can be changed. It can be changed. Molecular weight can also be adjusted by changing the amount of polymerization initiator, but if, for example, a large amount of polymerization initiator is used to lower the molecular weight, the heat generated by polymerization increases, making it difficult to perform polymerization operations. cause great difficulties. However, when a chain transfer agent is used, less heat is generated and a low molecular weight copolymer can be easily produced. . Copolymerization of the unsaturated monomers may be carried out according to a conventional method, and first, a mixture of each monomer and a chain transfer agent in a predetermined ratio is charged into a polymerization tank.

Regarding the charging method, the entire amount may be charged at once from the beginning of the polymerization, or only a portion may be charged at first, and the remainder may be gradually added by a dropwise method as the polymerization reaction progresses. The latter method is particularly advantageous for those where polymerization heat generation tends to be a problem, and in this case it is preferable to use a low molecular weight copolymer which has been previously polymerized on a small scale instead of a thinner. Is the polymerization initiator included in the mixture of the monomer and chain transfer agent? When the valley reaches the predetermined polymerization temperature, 0
Moreover, it is preferable to sufficiently replace the air in the polymerization tank with an inert gas such as nitrogen before adding it. In this polymerization reaction, the use of a chain transfer agent facilitates polymerization control, so no common agent is required as a medium. If it is desired to use a stimulant, for example n-hebutane, toluene, n-hexane, dioxane, methyl ethyl ketone, methyl isophthyl ketone, ethyl acetate, isof.

A solvent such as lopanol may be used. The polymerization temperature is
Although it varies from 0 depending on the type of monomer and polymerization initiator, a range of about 50 to 9,000 is generally suitable.

If the polymerization temperature becomes too high and generates too much heat, adjust it appropriately by cooling with water or the like. The polymerization time is
It mainly depends on the above polymerization temperature and the type of monomer.
The end point of the reaction is determined so that as little unreacted monomer remains as possible and no gelation occurs, but it is usually convenient to set the end point as the point at which no heat is generated. The acrylic low molecular weight copolymer thus obtained has an average molecular weight of about 1,000 to 200,000,
It is a liquid with low viscosity at room temperature.

In this invention, a specific amount of filler and/or rocking agent is blended into the acrylic low molecular weight copolymer,
A composition for forming an inner layer. The filler used here is one that moderates the viscosity of the composition and improves its conformability to irregularly shaped parts and the workability of hand smoothing, such as calcium carbonate, silica powder, talc, poppy seeds, magnesium oxide, Glass powder, magnesia, clay powder, titanium oxide, aluminum hydroxide, etc. are preferably used.

The blending amount should be 1 to 30 parts by weight per 10 parts by weight of the acrylic low molecular weight copolymer; if it is less than 1 part by weight, the above effect cannot be obtained, and if it is less than 300 parts by weight, If the amount increases, adhesion at room temperature will be impaired and it will be difficult to obtain desirable anticorrosion properties. Further, the bridge modifier used together with or in place of the filler improves the thixotropic properties of the composition, thereby improving the hand-leveling workability like the filler, For example, hydrogenated castor oil type surfactants, polyether/ester type surfactants, oxidized polyethylene type surfactants, etc. are used.

The blending amount should be 0.2 to 2 parts by weight based on 10 parts by weight of the acrylic low molecular weight copolymer, and the viscosity of the copolymer and filler should be adjusted within this range. The optimal blending amount is selected depending on whether the If the amount is less than 0.2 parts by weight, the above effects cannot be obtained, and if it is more than 2 parts by weight, the viscosity becomes too high and the workability of hand smoothing deteriorates. In addition to the above-mentioned components, the composition for forming an inner layer of the present invention may optionally contain a rust preventive such as tannic acid, a plasticizer, a pigment, an anti-aging agent, a fungicide,
Various additives such as antioxidants, ultraviolet absorbers, and ozone deterioration inhibitors can also be blended.

In addition, when using such a composition for the purpose of anticorrosive construction, it may be impregnated into a base material such as a nonwoven fabric and used in the form of a tape or the like. Next, the composition for forming an outer layer of the present invention can be formed into a film by applying the above-mentioned composition for forming an inner layer to the area to be coated with anticorrosion, and then applying it thereon and drying and curing at room temperature or under heating. It contains an epoxy resin and its curing agent as essential components.

As the epoxy resin used here, a glycidyl ether type epoxy resin is suitable.

Typical examples include bisphenol-based epoxy resins represented by the general formula (2) below, which are obtained by reacting bisphenol A and epichlorohydrin in the presence of an alkali, and reaction products between aliphatic glycols and epichlorohydrin. Examples include aliphatic epoxy resins represented by the general formula below. Commercially available products of the above pisphenol-based epoxy resin include Epikot #828 manufactured by Shell Chemical Co., Ltd. (average value of n in the general formula approximately 0.2) and Epikot #834 (average value of n in the general formula approximately 0.2). 0.6),
Picoat #1001 (the average value of n in the general formula is approximately 2.
3), and commercially available aliphatic epoxy resins include Epicote #812 manufactured by Shell Chemical Co., Ltd. and Eporite 20 plates and 60 plates manufactured by Kyoei Co., Ltd. (
(In both formulas, R is a residue of bisphenol A, R' is hydrogen or an alkyl group, and n is 0 or an integer) In addition to the above glycidyl ether type epoxy resin, the following general formula (2); (In the formula, n is 0 to 2) Any of the borac type epoxy resins and other conventionally known epoxy resins can be used.

In addition, commercially available products of the above-mentioned Borac type epoxy resin include Epicoat #152 and Epicoat #154 manufactured by Shell Chemical Co., Ltd. The curing agent used in combination with the above epoxy resin includes diaminodiphenyl ether, m
-phenylenediamine, 4-chloroo-phenylenediamine, o-phenylenediamine, toluenediamine,
In addition to aromatic amines such as benzicine and meta-aminobenzylamine, aliphatic polyamines such as polymethylene diamine, polyether diamine, and substituted polyamiso, it is also known as a curing agent for epoxy resins such as acid anhydrides. Any of these can be applied. The proportion of these curing agents used varies considerably depending on the type of hardening agent, but is generally used in the range of 2 to 10 parts by weight per 10 parts by weight of the epoxy resin. The outer layer forming composition containing such an epoxy resin and its curing agent may contain a thermoplastic resin such as acrylic rubber to impart flexibility to the layer formed therefrom, and the inner layer forming composition described above. There is no problem in similarly blending the various additives already mentioned as those that can be added to the product.

It is desirable that such an outer layer forming composition is such that the layer formed therefrom has an elongation of 20% or more.

This is because if the elongation is too small, cracks will occur in the outer layer when exposed to harsh conditions such as repeated heating and cooling after forming the anticorrosion layer, and the effect of providing this layer will be lost. . It goes without saying that such elongation properties can be easily obtained by selecting the type of epoxy resin and its combination with a curing agent, or by adding a malleability agent. It is something. The heat-resistant anti-corrosion coating material of the present invention consists of a two-component system of the composition for forming an inner layer and the composition for forming an outer layer as detailed above, and the proportion of both compositions used depends on the area to be coated with anti-corrosion. It can be determined as appropriate.

However, in general, the amount of the outer layer forming composition is in the range of 0.5 to 50 parts by weight based on the weight part of the inner layer forming composition 10. In terms of layer thickness, the thickness of the layer formed from the composition for forming an inner layer is 0.4 to 0.2cm, while the thickness of the layer formed from the composition for forming an outer layer is 0.01 to 0.2cm. It is best to have about 2 willows. Next, examples of this invention will be described.

In the following, parts and % mean parts by weight and % by weight. Example 1 A mixture consisting of 5 parts of n-butyl acrylate, 5 parts of ethyl acrylate, 1 part of acrylonitrile and 0.42 parts of 2-mercaptoethanol was prepared, and 30% of this mixture was added to 200 cc volume of four parts. The mixture was placed in a neck flask and heated to 7,000 ℃ under the ocean while flowing nitrogen.

After replacing the inside of this flask with nitrogen for about 50 minutes,
0.1 part of '-azobisisobutyronitrile was added. After the fever has subsided, add the remaining 70% of the above mixture.
% and 0.1 part of Q,Q'-azobisisobutyronitrile was added to the flask using a dropping funnel. It took a while to drip gradually. The polymerization reaction was terminated when no heat generation was observed. The acrylic low molecular weight copolymer thus obtained has a solid content (1
After heating and drying at 5,000°C for 30 minutes, the weight) was 99.1%, the molecular weight by vapor pressure osmosis was 29,000, and the viscosity (30oo) by a B-type viscometer was 8,200 poise.

This copolymer was blended with 10 parts of Kokeshi, 4 parts of magnesium oxide, and 3 parts of finely powdered silica, and kneaded in a planetary mixer to obtain a composition for forming an inner layer. Next, weaved 5 bales of Epicote #1001 (the above-mentioned epoxy resin), 1 anchor of tetramethylenebentamine, and Toacron #6.
01 (trade name, manufactured by Toa Paint Co., Ltd.; acrylic rubber) 10 base was added thereto, and the mixture was further adjusted to a 30% toluene solution to obtain a composition for forming an outer layer.

The above two compositions are used as the heat-resistant anti-corrosion coating material of the present invention, and the composition for forming an inner layer is first applied to the surface of the steel pipe with 35 ribs to form an inner layer with a thickness of 0.7 mm, and then an outer layer is formed. Apply the composition on the above inner layer and dry it at room temperature.
An outer layer having a thickness of 00A was formed. The elongation of the outer layer was 300%. The characteristics of the anticorrosion layer having the inner and outer two-layer structure thus formed were evaluated, and the results were as shown in the table below. Example 2 2-ethylhexyl acrylate 5 anchors, acrylic acid n-
A mixture consisting of 50 parts of butyl and 3.2 parts of lauryl mercaptan was prepared, and 30% of this mixture was added to 200 cc.
The mixture was placed in a four-necked flask and heated to 70 qo while flowing nitrogen.

After purging the inside of this flask with nitrogen for about 5 minutes, Q,Q
- 0.1 part of azobisisobutyronitrile was added. After the fever has subsided, add the remaining 70% of the above mixture.
% and 0.1 part of Q,Q'-azobisisobutyronitrile was gradually added dropwise into the flask using a dropping funnel over a period of 1.5 hours. The polymerization reaction was terminated when no heat generation was observed. The acrylic low molecular weight copolymer thus obtained has a solid content of 9.
9.4%, molecular weight 8,500, viscosity (3000)]
It was 20 poise.

This copolymer contains 10 parts of magnesium carbonate, 25 parts of magnesium carbonate, and 3 parts of pentaerythrityl-tetrakis (3.5-
One part of rt-butyl-4-hydroxyphenyl)propionate (trade name: Irganox #1010, manufactured by Ciba Car-Gee Co., Ltd.) was added to the mixture and kneaded in a planetary mixer to obtain a composition for forming an inner layer. Next, in a mixture of 10 parts of Epikote #828 (the above-mentioned epoxy resin) and 15 parts of the Eporite fertilizer (the above-mentioned epoxy resin),
20 parts of menthanediamine and 2 parts of m-phenylenediamine were added, and the mixture was further adjusted to a 30% toluene solution to obtain a composition for forming an outer layer. Using the above two compositions as the heat-resistant anti-corrosion coating materials of the present invention, a two-layer anti-corrosion layer was formed on the surface of the steel pipe in the same manner as in Example 1.

The inner layer had a thickness of 1.2 mm, the outer layer had a thickness of 130 A, and its elongation was 50%. Characteristic evaluation of this anticorrosion layer was as shown in the table below. Example 3 Acrylic acid n-
Butyl 10 anchor part, 2-hydroxyethyl acrylate 4
．． 3 parts, 2.5 parts of n-butyl mercaptan and Q,Q
An acrylic low molecular weight copolymer was obtained according to the method of Examples 1 and 2 using 0.2 part of '-azobisisoputilonitrile as a polymerization raw material.

The solid content of this copolymer is 99.4%, the molecular weight is 5,
200, and the viscosity (3000) was 95 poise. 0
This copolymer, 10 pieces of Ikari Seiko, 11 pieces of calcium carbonate, and 1 part of sulfuric acid were blended and mixed in a planetary mixer to obtain a composition for forming an inner layer.

Next, 5 base parts of 50% emulsion of Epicort #828 (mentioned above), 1 base part of Cucaresin H-30 (trade name, 50% emulsion of amine curing agent, manufactured by Yoshimura Yuka Co., Ltd.), and 1 anchor part of Toacron #2911 ( Toa Paint Co., Ltd. (trade name: 50% Emulsion of Acrylic Rubber Containing Glycidyl Group) 10 parts were added to prepare an outer layer forming composition. The above two compositions are used as the heat-resistant and anti-corrosion coating material of the present invention,
Thereafter, in the same manner as in Example 1, an anticorrosive layer having a two-layer structure, inside and outside, was formed on the surface of the steel pipe.

The inner layer has a thickness of 1 skin, the outer layer has a thickness of 80 cm, and its elongation is 1 skin.
It was 50%. Characteristic evaluation of this anticorrosion layer was as shown in the table below. Example 4 100 parts of ethyl acrylate, 6 parts of glycidyl acrylate
．． 5 parts, N-butyl mercaptan 9 parts and Q,Q'-
An acrylic low molecular weight copolymer was obtained according to the method of Examples 1 and 2 using 0.2 part of azobisisobutyronitrile as a polymerization raw material.

The solid content of this copolymer is 99.0%, the molecular weight is 1,
500, and the viscosity (30°) was 3,800 poise. This copolymer 10 base, 70 parts of Yuluk, 2 parts of Disparon #3600-N (trade name, manufactured by Kusumoto Kasei Co., Ltd.; polyenal ester type surfactant) as a thixotropic agent, and Irganox #1010 (previous life) 1 part was blended and mixed in a planetary mixer to obtain a composition for forming an inner layer. Next, 2 parts of toluene diamine and 15 parts of menthanediamine were added to 10 parts of Epikot #834 (the above-mentioned epoxy resin) and 10 parts of the Epikot #812 (the above-mentioned epoxy resin), and then 30% toluene was added. A solution was prepared to obtain an outer layer forming composition.

Using the above two compositions as the heat-resistant anti-corrosion coating materials of the present invention, a two-layer anti-corrosion layer was formed on the surface of the steel pipe in the same manner as in Example 1.

The thickness of the inner layer was 0.8 mm, and the thickness of the outer layer was 60 mm, with an elongation of 30%. Characteristic evaluation of this corrosion protection layer was as shown in the following table. (Note) 1) Betrolatum 10
When the surface of the steel pipe was coated with a betarolatum-based anticorrosive composition containing 0 parts of talc and 1 part of tannic acid, and then further coated with the outer layer forming composition of Example 3. These are the test results.

2) Drooping even if left at 150℃ for 24 hours If (○), the temperature is 150℃. The case where it drooped quickly was marked as (×).

3) Changes in the properties of the inner layer under each test condition were shown.

As is clear from the above test results, it can be seen that the heat-resistant and anti-corrosion coating material of the present invention has good sagging resistance and heat resistance, and can sufficiently exhibit anti-corrosion effects.

Claims (1)

[Claims] 1 Represented by the following general formula; ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is hydrogen or a methyl group, and R_2 is an alkyl group having 2 to 14 carbon atoms) Acrylic low molecular weight copolymer mainly composed of unsaturated monomers 1
00 parts by weight, 1 to 300 parts by weight of filler and/or
Alternatively, a heat-resistant anticorrosive coating material comprising an inner layer forming composition containing 0.2 to 20 parts by weight of a thixotropic agent and an outer layer forming composition containing an epoxy resin and a curing agent thereof. 2. The heat-resistant anticorrosive coating material according to claim 1, wherein the acrylic low molecular weight copolymer in the inner layer forming composition has a functional group that reacts with an epoxy resin or its curing agent in its molecule. . 3. The heat-resistant anti-corrosion coating material according to claim 1 or 2, wherein the composition for forming the outer layer is such that the elongation of the layer formed from the composition is 20% or more.