JPS6191217A - Protection of underwater structure - Google Patents

Abstract

PURPOSE:To make it possible to protect easily even in water an underwater structure with an anticorrosive paint film of excellent adhesion by an operation similar to one on land, by using a composition comprising a base resin obtained from an epoxy resin and a specified phosphoric acid compound and a curing agent. CONSTITUTION:A base resin is formed by mixing at least one compound selected from among a phosphoric acid having at least one P-OH bond, its ester and its salt (abbreviated as a phosphate compound) with an epoxy resin preferably at such a ratio that about 0.05-0.4 equivalent of the hydroxyl groups of the phosphate compound are present per equivalent of epoxy groups and heating the mixture (to about 80-110 deg.C). This base resin is mixed with a usual epoxy resin curing agent and preferably a filler to obtain a two-component composition. Desirable phosphate compounds include orthophosphoric acid, n-butyl or 2-ethylhexyl mono- or di-ester thereof and salts thereof with K, Na, or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for protecting underwater structures, and more particularly to a method for preserving underwater structures by effectively preventing corrosion and fouling of the structures.

In recent years, there has been an increase in the construction and construction of oil drilling rigs and oil Ii storage purges associated with offshore development, WA structures such as offshore plant ships, piers of giant bridges built on the ocean, and underwater steel structures for offshore airports. However, these steel structures are almost impossible to move from their installation areas for maintenance. Therefore, in the underwater part of these marine steel structures,
In addition, problems such as cleaning and maintenance of anti-corrosive coatings in the splash zone have arisen, and the need for maintenance at sea has become a major issue. As one means for solving this problem, a method can be considered 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.

As such conventionally known compositions for underwater coating, there are compositions based on epoxy resin, using polyamide or polyamine as a hardening agent, and adding a filler 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-mentioned 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 use in epoxy resins. 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 a small number of P-OH bonds and 1 WA, the original properties of the epoxy resin can be improved. In addition to maintaining the excellent coating film performance and curability, the phosphoric acid compound and the epoxy resin cooperate to develop smooth and excellent adhesion in water. For this reason, when a composition consisting of (a) and (b) above is applied to an underwater structure, the adhesion force is extremely large, so it hardens as it is without being washed away by waves etc. before hardening, and the cured film is Due to its strong adhesion, it firmly adheres to underwater structures. 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, and usually, for 1 equivalent of epoxy groups in the epoxy resin, The hydroxyl group of the phosphoric acid compound is 0.
05-0. The heat treatment is performed at a mixing ratio of g equivalent, preferably 0.05-0.4.

The heating temperature at this time is usually about 50-130°C, preferably about 80-110°C. Although a solvent is not necessarily required in this reaction, the reaction may be carried out in the presence of a solvent. The best solvent for this is toluene.
Typical examples include xylene, styrene, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl butyl ketone, etc. These solvents are usually used in an amount of about 10-100 parts by weight per 100 parts by weight of the base resin. be. The base resin thus obtained has an epoxy equivalent of 3000 or less, preferably 190-2000.
That's about it.

The epoxy resin used as a raw material for the base resin in the present invention has a substituted or non-@ substituted glycidyl ether group represented by the following formula (where Z represents a hydrogen atom, a methyl group, or an ethyl group) in its molecule. Those having at least one can be typically used, and for example, diglycidyl ether of bisphenol, diglycidyl ether of bisphenol F, phenol novolac epoxy resin, diglycidyl ether of alkylene oxide adducts of bisphenols, etc. can be used. ,
There is no particular restriction on the epoxy equivalent, but preferably about 1 so-iooo of epoxy equivalents.

The phosphoric acid compound used in the present invention is phosphoric acid having at least one P-OH bond, its ester or its salt, and examples of the phosphoric acid include orthophosphoric acid,
Examples include metaphosphoric acid, birophosphoric acid, 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 human O esters.
xyalkyl esters such as ethyl, n-butyl, 2
Examples thereof include those having groups such as -ethylhexyl, hydroxyethyl, hydroxybutyl, hydroxypropyl, and droxypentyl, and mono- or diφ phosphate esters of n-butyl or 2-ethylhexyl are particularly preferred. Examples of phosphoric acid salts include the above-mentioned phosphoric acid salts, such as potassium, sodium, lithium, calcium, zinc, aluminum, tin, barium salts, among others, potassium, sodium, and calcium salts. Mono- or di-phosphates 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 per equivalent of epoxy group, in the case of amino group, 1 m1 of amine, in the case of carboxyl group, and 1,1 anhydride per equivalent of acid. The acid anhydride 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 ordinary ones such as calcium carbonate, talc, clay, bentonite, carbon black, and white carbon. It is used in amounts ranging from -1 to 300 parts by weight per 100 parts by weight of the total base.

Various additives including other epoxy resins can be used in combination with the composition used in the present invention, if necessary.
Specific examples of additives in this case include diluents, solvents, coloring pigments, and antirust pigments.

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 the 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 applied, such as brush coating, roll coating, spatula coating, mechanical coating, etc. The viscosity is preferably about 20-500 poise for brush application 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 heavy parts.

Example 1 Bisphenol A diglycidyl ether (epoxy ffi 260) 100 parts, alkyl (carbon v118
) Monoglycidyl ether (epoxy fi 330)
25 parts and 6 parts of orthophosphoric acid were mixed and reacted at 80°C for 5 hours to obtain base resin [I].

The base resin (11,100 parts) was mixed with 35 parts of aromatic modified polyamine (amine value: 270, aromatic diamino diphenylmethane, molecule: 1,250), 20 parts of talc, and 30 parts of glass flakes 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 occurrence of chains were measured.The results are shown in Table 1 below.However, the steel plate used was shot-blasted. Immediately after, 3 hours; WA temporary immersed in salt water for 1 day.

Example 2 Instead of using 30 parts of aromatic modified polyamine alone as a curing agent in Example 1, 5 parts of the 30 parts were replaced with aliphatic polyamine (amine value 370, metaxylylene diamine, Molecule 1250) was used, and all other procedures were carried out in the same manner as in Example 1.

Example 3 - 100 parts of bisphenol F diglycidyl ether (fi: 280), bisphenol A
- 50 parts of diglycidyl ether of propylene oxide adduct (epoxy equivalent: 340) and 17 parts of dibasic potassium phosphate were mixed and reacted with stirring at 110°C for 5 hours to obtain base resin [n].

Aromatic modified polyamine (amine value 270) as an epoxy resin curing agent for 100 parts of this base resin [[]
30 parts of xylene, 20 parts of barium sulfate, and 30 parts of glass flakes were mixed to prepare a composition of the present invention. Using this, the same physical properties as in Example 1 were measured. The results are also listed in Table 1 below.

Comparative Example 1 45 parts of aliphatic polyamine (amine (ilIi = 370),
A comparative composition was obtained by mixing 20 parts of talc and 30 parts of glass flakes. 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 - Aromatic modified polyamine was added to 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). (amine value 270) 40 parts, talc 20 parts,
and 30 parts of glass flakes were mixed to obtain a comparative composition. The same test as in Example 1 was conducted using this. 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 --- 9x 1,00x 100mm+ dull steel plate coating method - After soaking the above steel plate in salt water for a predetermined time,
The composition was brushed while immersed and cured in the vertical position.

Initial adhesion: Observe the condition immediately after brush application and follow the following evaluation: 0: Good (adheres just by brushing) △: Possible (adheres after brushing 2-3 times) )
%RH), cut the coating film with a cutter after 1 day, glued the measurement dolly with adhesive, and after 30 minutes
Measurement was performed using an Elcometer at 3°C and 60% RH.

The presence or absence of chains was examined by visually observing the two surfaces where chains were generated.

Table 1 (Hereinafter, -L-)

Claims (2)

[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) a curing agent for epoxy resin. 1. A method for protecting an underwater structure, which comprises protecting the underwater structure using a two-component composition comprising as main ingredients. (2) The protection method according to claim 1, characterized in that the base resin and/or the curing agent contain a filler.