JPH0572403B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for protecting underwater structures, and more particularly to a method for protecting underwater structures by effectively preventing corrosion and staining of the structures. In recent years, the construction and construction of oil drilling rigs and oil stockpile purges associated with offshore development, steel structures for offshore plant ships, piers of huge bridges built on the ocean, underwater steel structures for offshore airports, etc. has been increasing. However, it is almost impossible to move these steel structures from their installation areas for maintenance. Therefore, problems such as cleaning and maintenance of anti-corrosive coatings occur in underwater parts of these marine steel structures or in splash zones, and the need for maintenance at sea has become a major issue. One possible means for solving this problem is to form a coating with excellent corrosion resistance on the underwater parts and splash zones of these underwater structures using the same simple and easy means as on land. Conventionally known underwater coating compositions include epoxy resin-based compositions,
There are compositions in which a polyamide or polyamine is used as a hardening agent and a filler is added thereto. However, this known composition has weak adhesion and is easily washed away by waves during curing, and even if it is cured, the adhesion of the cured product is insufficient and long-term corrosion protection cannot be expected at all. It's something that doesn't exist. The purpose of the present invention is to develop an underwater coating composition that can be easily coated underwater by the same operations as on land, and that can form a coating with excellent adhesion and high corrosion resistance. An object of the present invention is to provide a method that can effectively protect underwater structures. The above objects of the present invention are (a) a base resin comprising at least one phosphorus acid having at least one P-OH bond, an ester thereof and a salt thereof, and an epoxy resin; and (b) a base resin for epoxy resin. This is achieved by protecting underwater structures using a two-component composition comprising a curing agent as a main component. In the present invention, by using an epoxy resin as a base resin, and especially phosphoric acid, its ester, or its salt (hereinafter referred to as a phosphoric acid compound) having at least one P-OH bond, the original properties of the epoxy resin can be improved. In addition to maintaining the excellent coating film performance and curability of the epoxy resin, the phosphoric acid compound and the epoxy resin exhibit extremely excellent adhesion in water. For this purpose, when a composition consisting of (a) and (b) above is applied to an underwater structure,
Because of its extremely high adhesion, it will not be washed away by waves or the like before it hardens, and will harden as it is, and the cured film will adhere firmly to underwater structures due to its high adhesiveness. In addition, the cured coating film retains the original excellent properties of epoxy resin, so it has extremely excellent corrosion resistance and other properties.In the end, all of these characteristics combine to provide extremely excellent corrosion protection.
This effectively protects underwater structures. It should be noted that the fact that the adhesion of epoxy resin in water can be significantly improved by using a phosphoric acid compound and epoxy resin together is something that was completely unknown and unknown, and was discovered for the first time as a result of many years of research by the present inventor. This is a surprising new fact discovered. The base resin used in the present invention can be manufactured from a phosphoric acid compound and an epoxy resin, and these are usually mixed in a proportion that leaves epoxy groups.
Normally, per equivalent of epoxy group in epoxy resin,
The heat treatment is performed at a blending ratio of 0.05 to 0.9 equivalents, preferably 0.05 to 0.4 equivalents of hydroxyl groups in the phosphoric acid compound. The heating temperature at this time is usually about 50-130℃, preferably
Perform at about 80-110℃. Although a solvent is not necessarily required in this reaction, the reaction may be carried out in the presence of a solvent. Examples of solvents used in this case include toluene, xylene, styrene, acetone,
Typical examples include methyl ethyl ketone, methyl isobutyl ketone, and methyl butyl ketone, and the amount of these solvents used depends on the base resin.
It is usually about 10-100 parts by weight per 100 parts by weight. The base resin thus obtained has an epoxy equivalent of 3,000 or less, preferably about 190-2,000. The epoxy resin used as a raw material for the base resin in the present invention has the following formula:

Those having at least one substituted or unsubstituted glycidyl ether group in the molecule can be typically used, such as bisphenol A. Diglycidyl ether of bisphenol F, phenol novolac epoxy resin, siglycidyl ether of alkylene oxide adducts of bisphenols, etc. can be used, and the epoxy equivalent is not particularly limited, but preferably An epoxy equivalent of about 150-1000 is good. The phosphoric acid compounds used in the present invention include phosphoric acid having at least one P-OH bond;
It is an ester or a salt thereof, and examples of phosphoric acid include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid,
Examples include phosphorous acid, polyphosphoric acid, phosphonic acid, phosphinic acid, and orthophosphoric acid is particularly preferred.
Examples of phosphoric acid esters include the above-mentioned phosphoric acid esters, preferably alkyl esters having about 8 or less carbon atoms (those having one or more hydroxyl groups) and hydroxyalkyl esters, such as ethyl, n
-butyl, 2-ethylhexyl, hydroxyethyl, hydroxybutyl, hydroxypropyl, hydroxybentyl, etc.
Particularly preferred are mono- or di-phosphoric acid esters of n-butyl or 2-ethylhexyl. Also, examples of phosphoric acid salts include the above-mentioned phosphoric acid salts, such as potassium,
Examples include salts of sodium, lithium, calcium, zinc, aluminum, tin, barium, etc.
Among these, primary or secondary phosphates of potassium, sodium, and calcium are preferred. As the curing agent used in the present invention, all of the usual curing agents for epoxy resins can be used in a wide range, such as aliphatic polyamines, aromatic modified polyamines, alicyclic polyamines, polyamides, amino acids, etc. Examples include resins and carboxylic acids. The amount of these curing agents used is also the amount used as a normal curing agent, and usually for 1 equivalent of epoxy group, amine equivalent for amino group, acid equivalent for carboxyl group, and acid anhydride for acid anhydride. The physical equivalent is about 0.5-2.5 equivalent. In addition, in the present invention, a filler can be used in combination, and the use of this filler improves underwater workability by adjusting viscosity and specific gravity, prevents peeling of the coating film due to the influence of waves, and adjusts and uniformizes the thickness of the coating film. Effects such as improved leveling, improved mechanical strength of the cured product, and stress relaxation can be expected. This filler may be mixed in advance with the base resin or with the curing agent, or the base resin, curing agent, and filler may be mixed at the same time. A wide variety of fillers are used at this time, including calcium carbonate, talc, clay, bentonite, carbon black,
Common examples include white carbon, which is used in an amount of 1 to 300 parts by weight per 100 parts by weight of the base resin and curing agent. Various additives including other epoxy resins can be used in combination with the composition used in the present invention, if necessary. Examples of additives in this case include diluents, solvents, coloring pigments, and antirust pigments. , etc. can be cited as specific examples. When protecting an underwater structure using the composition of the present invention, the composition of the present invention is applied to the underwater part or splash part of the underwater structure. As the coating means at this time, any of the various means similar to those used on land can be effectively used, such as brush coating, roll coating, spatula coating, mechanical coating, etc. The viscosity should be 20-500 poise for brush or roll application, and 500-2000 poise for spatula application. EXAMPLES The present invention will be specifically described below with reference to Examples. However, in the following examples, parts indicate parts by weight. Example 1 100 parts of bisphenol A diglycidyl ether (epoxy equivalent: 260), 25 parts of alkyl (carbon number 18) monoglycidyl ether (epoxy equivalent: 330), and 6 parts of orthophosphoric acid were mixed and reacted at 80°C for 5 hours. base resin

I got [ ]. The base resin

[ ] 35 parts of aromatic modified polyamine (amine value: 270, aromatic: diaminodiphenylmethane, molecular weight: 250), 20 parts of talc and 30 parts of glass flakes were mixed with 100 parts to obtain a composition of the present invention. When this composition was applied to a steel plate, the initial adhesion, adhesion after curing, cohesive failure rate, and rust occurrence were measured. The results are shown in Table 1 below. However, the steel plate used was one that had been immersed in 3% salt water for one day immediately after shot blasting. Example 2 Instead of using 30 parts of the aromatic modified polyamine alone as the curing agent in Example 1, 5 parts of the 30 parts were replaced with resin polyamine (amine value 370,
Using meta-xylylene diamine (molecular weight 250),
All other treatments were carried out in the same manner as in Example 1. Example 3 100 parts of bisphenol F/diglycidyl ether (epoxy equivalent: 280), 50 parts of diglycidyl ether of bisphenol A/propylene oxide adduct (epoxy equivalent: 340), and 17 parts of dibasic potassium phosphate were mixed. The base resin was then reacted with stirring at 110°C for 5 hours.

I got [ ]. This base resin

[ ] 30 parts of aromatic modified polyamine (amine value 270) as an epoxy resin curing agent per 100 parts,
A composition of the present invention was prepared by mixing 50 parts of xylene, 20 parts of barium sulfate, and 30 parts of glass frame. Using this, the same physical properties as in Example 1 were measured. The results are also listed in Table 1 below. Comparative Example 1 100 parts of unmodified bisphenol A diglycidyl ether (epoxy equivalent: 190), 45 parts of aliphatic polyamine (amine value: 370), 20 parts of talc
and 30 parts of glass flakes were mixed to obtain a comparative composition. Physical properties were measured in the same manner as in Example 1 using this composition. The results are shown in Table 1 below. Comparative Example 2 For 75 parts of unmodified bisphenol A/diglycidyl ether (epoxy equivalent: 190) and 25 parts of bisphenol A/propylene oxide adduct diglycidyl ether (epoxy equivalent: 340),
40 parts of aromatic modified polyamine (amine value 270),
Mix 20 parts of talc and 30 parts of glass flakes,
A comparative composition was obtained. Using this, the same test as in Example 1 was conducted. The results are shown in Table 1 below.
However, the methods for measuring each physical property in Table 1 below are as follows. Steel plate: Dull steel plate of 9 x 100 x 100 mm Coating method: The above steel plate was immersed in salt water for a predetermined time, and the composition was applied with a brush while immersed, and cured in a vertical position. Initial adhesion: Observe the condition immediately after brush application and follow the following evaluation: ○...Good (adheres just by brushing) △...Possible (adheres after brushing 2-3 times) × ...Poor (does not adhere) Adhesion after curing: Paint sample is placed in the atmosphere (23℃,
After one day, the coating film was cut with a cutter, a measurement dolly was attached using adhesive, and 30 minutes later, measurements were taken at 23°C and 60% RH using an Elcometer. Occurrence of mirrors: The presence or absence of mirrors was examined by observing the surface with the naked eye.

[Table] Comparative Example 3 65 parts by weight of "Epicoat #815", 35 parts of polyamide resin "Tomide 5002" (product name: Fuji Kasei Kogyo Co., Ltd.), and glass flake "CCF-45"
(Product name: Nippon Glass Fiber Co., Ltd.) 52 parts, barium sulfate
27 parts by weight, 20 parts by weight of titanium dioxide, "Bentone 34"
(Product name: National Red Co., Ltd.) 1 part was mixed and dispersed using a disper type stirrer to obtain an underwater curable coating composition. Comparative Example 4 A curing agent was synthesized by mixing 1.2 mol of diethylenetriamine with 1 mol of bisphenol A.
Add 10g of this curing agent to 10g of "Epicoat #828" and 3
g of TiO ₂ as a base agent to obtain an underwater curable coating composition. Comparative Example 5 “Sumi Epoxy ELA-125” (Sumitomo Chemical Co., Ltd.)
Product name: Bisphenol A epoxy resin) 100
After kneading 30 parts of No. 7 silica sand, 10 parts of calcium carbonate, and 10 parts of "diet cement" (trade name of Sumitomo Cement Co., Ltd.), 4,4'-diaminodiphenylmethane was produced by the reaction between aniline and formaldehyde. 200 parts of the distillation residue (softening point: 44°C, nitrogen content: 14%), which is a by-product during the production, was added to a stirrer, a thermometer, a reflux condenser,
Pour into a flask equipped with a dropping funnel and heat to 90°C. After adding 32.5 parts of n-butyl glycidyl ether at 90 to 100°C, the mixture was kept at 100°C for 1 hour.
The reaction was completed. This reactant was added with 230 parts of di-n-butyl phthalate and salicylic acid as a promoter.
A paint was obtained by mixing 60 parts of a curing agent with 46 parts added thereto. Comparative example 6 Dow Chemical epoxy resin “DER-331J”
(Epoxy equivalent: 186-192) and 15 parts of 1,3,6-triaminomethylhexane were mixed to obtain an underwater curable coating composition. Comparative Example 7 100 parts of bisphenol A diglycidyl ether (epoxy equivalent = 260) and
25 parts of "ED-501" (epoxy equivalent = 300) and 6 parts of orthophosphoric acid were mixed and reacted at 80°C for 5 hours, and the obtained precondensate was designated as [1]. 30 parts of polyamide (amine value = 340) as an epoxy resin curing agent was added to 100 parts of precondensate [1] to obtain an underwater curable coating composition. Various physical properties of the above Comparative Examples 3 to 7 were measured in the same manner as in Example 1. The results are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1. (a) A base resin obtained from an epoxy resin and at least one of phosphoric acid, its ester, and its salt having at least one P-OH bond, and (b) an epoxy resin. 1. A method for protecting an underwater structure, which comprises protecting the underwater structure using a two-component composition containing a curing agent for resin as a main component. 2. The protection method according to claim 1, wherein the base resin and/or the curing agent contain a filler.