JPH01172469A - Primer excellent in hot water resistance for polyolefin-coated steel material - Google Patents

Abstract

PURPOSE:To obtain the title primer which can improve all of the high- temperature adhesiveness, hot water resistance and resistance to peeling from a cathode at high temperatures of a polyolefin-coated steel material, by using an epoxy resin, a modified polyamine and an inorganic pigment as essential components. CONSTITUTION:The title primer which is interposed in between a steel material and a polyolefin and is excellent in hot water resistance and resistance to peeling from a cathode at high temperatures is obtained by using an epoxy resin (A) comprising a bisphenol A epoxy resin, a bisphenol AD epoxy resin or a mixture thereof, a modified polyamine formed by an addition reaction of 1mol. of a condensate of m-xylenediamine with epichlorohydrin with 0.2-0.6mol. of at least one member (B) selected from among butyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether and ethylhexyl glycidyl ether and an inorganic pigment (C) as essential components.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a primer composition for polyolefin-coated steel. Specifically, it is interposed between the steel material and the polyolefin. This invention relates to a primer for polyolefin-coated steel that has excellent hot water resistance and high-temperature cathode peelability.

Prior art steel materials often corrode considerably when exposed to the atmosphere, underground, or sea water without any protection from the surrounding environment. As a countermeasure against this corrosion, a polyolefin coating such as polyethylene or polypropylene, which has excellent chemical stability, is applied. In recent years, as the demand for energy has increased and the development of resources such as oil, heavy oil, and geothermal energy from the seabed and polar regions has become more active, the durability of polyolefin coatings on steel structures and line pipes in high-temperature grafting environments has increased. This has become a problem.

Polyolefin resins are generally non-polar due to their chemical structure, so
Since direct adhesion is difficult to the surface of steel materials, a method of coating polyolefin resin through adhesive polyolefin modified with unsaturated carboxylic acid or its acid anhydride has been adopted. However, when immersed in an environment containing electrolytes such as seawater or salt water, or in a moist soil environment, the adhesive strength decreases in a short period of time at temperatures near room temperature, and rust occurs between the steel material and the coating.

In addition, in an environment where cathodic protection is used in combination, there are drawbacks such as the coating being easily peeled off starting from coating defects (cathode peeling) due to excessive corrosion protection current.

Therefore, in order to solve these drawbacks, a method of further applying a chromate-based chemical conversion treatment between the steel material to be protected against corrosion and the adhesive polyolefin (JP-A-52-143934, JP-A-54
-1201181) and a method using a thermosetting epoxy primer (JP-A-58-143223, JP-A-5
No. 9-222275) and the like have been proposed, which have a remarkable effect on improving water-resistant adhesion near room temperature. However, it is difficult to maintain adhesive strength for a long time in a grafting environment of over 60°C, and the polyolefin coating has excellent water resistance in hot water over 80°C and hot brine, that is, excellent hot water resistance and high-temperature cathodic peeling resistance. Development of steel materials is desired.

Problems to be Solved by the Invention An object of the present invention is to provide a primer for polyolefin-coated Mi steel materials that has excellent hot water resistance and high-temperature cathode peeling resistance.

Means for Solving the Problems The present inventors have developed the hot water immersion resistance of polyolefin-coated steel,
As a result of intensive studies to resolve the shortcomings regarding high-temperature cathode peelability, we developed a modification in which an alkyl glycidyl ether was added to a condensate of 1m-xylene diamine and epichlorohydrin to a specific epoxy resin and an inorganic pigment between the steel material to be protected and the adhesive polyolefin. The present invention has been completed based on the discovery that the above-mentioned problems can be solved by interposing a primer composition containing a polyamine curing agent.

That is, the present invention provides the following (A), (B), (C
This is a primer for laminating steel and polyolefin, which is characterized by containing the following three components as essential components.

(A) An epoxy resin consisting of a bisphenol A epoxy resin, a bisphenol AD epoxy resin, or a mixture thereof.

(B) One or more of butylglycidyl ether, phenylglycidyl ether, 0-cresylglycidyl ether, and ethylhexylglycidyl ether at 0.2 to 0.0% per mole of the condensate of m-xylene diamine and epichlorohydrin. Modified polyamine reacted and added at a ratio of 8 moles.

(C) Porcelain pigment.

Function First, in the present invention, the steel material is a general term for steel pipes, shaped steel, copper strips, steel bars, etc., which are widely used outdoors, underground, in the sea, under the sea, etc.

Next, the structure of the laminate of the steel material and polyolefin of the present invention will be explained.

FIG. 1 is a schematic diagram showing one embodiment of a laminate of steel and polyolefin. A laminate is formed by sequentially forming an epoxy primer layer 2 containing the three components (A), (B), and ((:) above, a modified polyolefin adhesive layer 3, and a polyolefin anticorrosion layer 4 on the surface of a steel material 1 to be protected against corrosion. It is coated.

In addition, a phosphate treatment film is applied to the boundary between the epoxy primer layer 2 and the steel material 1 to be protected against corrosion in order to further improve adhesion and corrosion resistance.
It is effective to provide a chemical conversion treatment layer such as a chromate treatment film.

In addition, in order to improve the strength and thermal deformability of the polyolefin anticorrosion layer 4, the anticorrosion layer may have a two-layer structure, with the upper layer being a polyolefin layer containing a fibrous substance or a scaly substance, and the lower layer being a polyolefin resin layer. good.

Next, the epoxy primer composition of the present invention will be explained.

The epoxy primer composition used for polyolefin laminated steel materials as shown in Figure 1 contains butylglycidyl per mole of (A) an epoxy resin of ff1 min and (B) a condensate of m-xylene diamine and epichlorohydrin. A modified polyamine curing agent prepared by reacting and adding one or more of ether, phenyl glycidyl ether, 0-cresyl glycidyl ether, and ethylhexyl glycidyl ether at a ratio of 0.2 to 0.6 mole as a vehicle, ( C) Pigment, which is a component, has a pwc of 3 to 45
This is an epoxy-based primer characterized by containing %.

The epoxy resin that is component (A) is bisphenol A
type of glycidyl ether, or bisphenol AD
It is preferable that the epoxy equivalent is 170 to 2150 from the standpoint of hydrothermal properties.

Bisphenol A type diglycidyl ether typically has the following molecular structure, and commercially available products correspond to the trade names in Table 1, for example.

(Left below) Table 1 Bisphenol AD type diglycidyl ether has the following molecular structure, such as Evomic R-710 and R-71 commercially available from Mitsui Petrochemical Co., Ltd.
This corresponds to 0H.

Note that an epoxy resin with hydrolyzable chlorine suppressed to 0.05% or less, such as Epomic R-140p shown in Table 1, may also be used.

What is a modified polyamine curing agent in which furkyl glycidyl ether is added to a condensate of m-xylene diamine and epichlorohydrin as component (B)?

A condensate of m-xylene diamine and epichlorohydrin (e.g. Gascamine G328 manufactured by Mitsubishi Gas Chemical Co., Ltd.) having the structure I and in which the R group is a butyl group or a phenyl group, and where n is in the range of 1 to 4. This is a curing agent prepared by addition-reacting glycidyl ether, which is either a 0-cresyl group, an 0-cresyl group, or an ethylhexyl group, in a ratio of 0.2 to 0.6 mole.

If the R group is other than the above-mentioned groups, the object of the present invention cannot be achieved due to poor resistance to immersion in hot water.

Further, the addition ratio of the above glycidyl ether is preferably in the range of 0.2 to 0.6 mol per 1 mol of the condensate of m-xylene diamine and epichlorohydrin, and this ratio is 0.2 mol. If less than
The hot water immersion resistance decreases, and if the amount exceeds 0.8 mol, the viscosity increases significantly during synthesis.

Since the composite becomes a hard solid, it is difficult to put it into practical use.

The manufacturing method of these curing agents is described in Japanese Patent Application Laid-Open No. 59-33321.
etc. are disclosed.

The blending ratio of the epoxy resin (A) and the modified polyamine (B) is determined from the viewpoint of hot water resistance by the number of equivalents of epoxy groups/the number of equivalents of active hydrogen of the modified polyamine=! /1, that is, an equireactive equivalent ratio is desirable.

Inorganic pigments that are component (C) include, for example, alumina, silica, titanium oxide, talc (rootstock magnesium silicate), kaolin clay, scaly mica (biotite, muscovite,
Colorings such as extender pigments such as micaceous iron oxide, synthetic iron oxide red, synthetic iron oxide yellow, cobalt blue, cobalt green, cobalt violet, strontium yellow, manganese violet, chromium oxide, red iron oxide, carbon black, and aluminum powder. Pigments, alkaline earth phosphate compounds (e.g. zinc phosphate), aluminum phosphates (e.g. aluminum tripolyphosphate), alkaline earth metal chromates (e.g. basic zinc chromate), phosphomolybdic acid compounds, silicomolybdic acid It is one type or a mixture of two or more types of anticorrosion pigments such as compounds, tungstic acid compounds, tungstic acid compounds, barium sulfate, and red lead.

Furthermore, in order to improve wettability with the epoxy resin, the surface of the L pigment may be chemically treated such as silane treatment, aluminum-silica treatment, phosphoric acid treatment, etc. The blending amount of the 11-free pigment is as follows: Epoxy resin 1 which is the component (A)
It is desirable to add 3 to 45 parts by weight per 00 parts by weight.

In addition to these components (A), CB) and (C), two ingredients are added to adjust the curing time of the epoxy primer paint.
It is also possible to blend additives such as accelerators such as -ethyl-4-methylimidazole and 2.4.6-tris(dimethylaminomethyl)phenol, reactive diluents, and viscosity modifiers.

The primer of the present invention is produced, for example, as follows.

By pre-mixing the pigment and additives in proportion to the blended amount for each of the epoxy resin (base resin) which is the component (A) or the curing agent which is the component (B), and then dispersing it by roll.・Pigment particle size is 5L to 401L
Dispersions of the base agent and curing agent are obtained.

The main agent and curing agent are stirred and mixed during use to create a uniform coating.
Paint the steel material by selecting an appropriate method from conventionally known methods such as airless spraying, roll painting, and ironing.

This coating film thickness, that is, the film thickness after heat curing of the epoxy primer layer shown in Figure 1, is 20% from the viewpoint of hot water resistance and coating cost.
Kawa - 300 IL is preferred; if the particle size of the dispersed pigment is less than 5L, the surface area of the pigment becomes large and the viscosity of the paint becomes extremely high, making painting difficult; if it exceeds 40IL, the spray nozzle may become clogged or the epoxy The surface of the primer coating becomes rough and the adhesive strength decreases.

In addition, the polyolefin resin referred to in the present invention includes conventionally known polyolefins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and polypropylene, as well as ethylene-propylene block or random copolymers, and polyamides. - Conventionally known polyolefin copolymers such as propylene block or random copolymers can be used.

In addition, the modified polyolefin resin may be a conventionally known polyolefin resin such as one obtained by modifying the above polyolefin resin with an unsaturated carboxylic acid such as maleic acid, acrylic acid or methacrylic acid, or one obtained by diluting the modified product with a polyolefin resin as appropriate. Modified polyolefins can be used.

A detailed explanation will be given below based on examples.

Examples To specifically explain the present invention, Table 2 shows Examples 1 to 41 of primer compositions according to the present invention.

In addition, as comparative examples, Comparative Examples 1 to 4 of brimer compositions corresponding to JP-A No. 58-143223, and JP-A No. 60-245
Comparative Examples 5 to 31 of primer compositions corresponding to No. 544 and Comparative Examples 32 to 40 of primer compositions other than the above are shown in Table 2.

In addition, the epoxy resins used in the Examples and Comparative Examples listed in Table 2 are listed in Table 3, the curing agents are listed in Table 4, and the inorganic pigments are listed in Table 5.
Each is shown in the table.

The amounts of the curing agent and inorganic pigment listed in Table 2 are expressed in parts by weight per 100 parts by weight of the epoxy resin. The amount of solvent added is parts by weight per 100 parts by weight of the brimer. In addition, in the Examples and Comparative Examples shown in Table 2, the inorganic pigments were premixed in proportion to the mixing ratio of the epoxy resin and the curing agent, and then processed in a paint roll mill to a particle size of 40 IL or less. Dispersed to cover a range.

The epoxy resin in which the above inorganic pigment is dispersed and a curing agent are mixed so that the epoxy groups of the epoxy resin and the active hydrogen of the curing agent have equal chemical equivalent values, and if the viscosity of the mixture is high, a solvent is added to the mixture. was added and diluted.

Next, a method for producing a high-density polyethylene-coated steel plate using the primers shown in Table 2 will be explained.

Grid blasted steel plate (100 layer width x 3
Preheat the 00 Hoencho x 8 - thickness) and set the surface temperature to 180.
℃ 0 Next, the primer shown in Table 1 was coated with a spray paint machine to a film thickness of 10 OJ and cured. Next, powdered maleic anhydride modified linear low density Polyethylene was electrostatically coated to a film thickness of 200%, melted, and then a high-density polyethylene sheet (100% obtained by press molding) was applied to the surface.
A sheet with a length of 300 mm and a thickness of 2.5 mm, which had been preheated to 200° C., was crimped to create a high-density polyethylene-coated steel plate.

In addition, phosphoric acid was applied to the surface of the grid-blasted steel plate using the same method as the above-mentioned method for producing the high-density polyethylene coated steel plate.
Silica-based chromate treatment agent (P 043-/total chromium weight ratio = t, te, and silica/total chromium weight ratio = 1.2
θ) was roll-coated so that the total chromium deposition amount was 520 mg/rn', preheated and baked, and the surface temperature was raised to 190°C. High-density polyethylene-coated steel sheets were subsequently created in the same manner and compared. .

Adhesion test on the above high-density polyethylene coated steel plate (measurement temperature 90°C, peel angle 900, peel speed 50 m5/
), hot water immersion test (immersion temperature 95℃, immersion time 400℃), hot water immersion test (immersion temperature 95℃, immersion time 400℃
0 hours, adhesion test conducted after immersion), cathode peel test [(initial Holliday diameter 51φ, electrolyte 3% NaCl, voltage -1,
5V (Cu/CuSO4, standard electrode), test temperature 90
℃, test time 2000 hours], and after the test, the peeling distance of the coating ((X-5)/2■■, X is the coating peeling diameter after the test) was measured. The results are shown in Table 6.

As is clear from the results in Table 6, as a surface treatment for steel, diglycidyl ether of bisphenol A or diglycidyl ether of bisphenol AD may be used singly or as a mixture, butyl glycidyl ether may be added to the condensate of m-xylene diamine and epichlorohydrin, If a primer consisting of an inorganic pigment and a modified polyamine to which one of phenyl glycidyl ether, 0-cresyl glycidyl ether, or ethylhexyl glycidyl ether is reacted is applied, it can be used in high-temperature adhesion tests, hot water immersion tests, and high-temperature cathodes. In the peel test, extremely good results not seen before can be obtained. Furthermore, when applying the primer according to the present invention and conventionally known chromate treatment in combination with the surface treatment of the steel material, high-temperature cathodic peeling resistance can be improved.

(Leaving space below) Table 6 (1) Table 6 (2) Table 6 (3) Table 6 (0 Table 6 (5) Table 6 (6) J (Adhesive strength (h/cm)), Measurement temperature 90℃1
2 (Adhesion strength after immersion in 95℃ hot water for 4000 hours (kg/c ■)), adhesive force measurement temperature 80℃ Book 3 (Peeling distance [■]), measurement temperature 90℃, test time 2000 hours Effects of the Invention As is clear from the examples, the primer for polyolefin-coated steel according to the present invention is superior to the conventional polyolefin-coated primer.
Since it forms a primer layer with excellent hot water resistance compared to the primer layer for steel materials, it dramatically improves both the high temperature adhesion, hot water resistance, and high temperature cathodic peelability of polyolefin-coated steel materials.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a polyolefin-coated steel material using a primer according to the present invention. 1... Steel material to be protected from corrosion, 2... Epoxy primer layer, 3... Fist-modified polyolefin adhesive layer, 4... Polyolefin anti-corrosion layer.

Claims (1)

[Claims] 1. A primer for laminating steel and polyolefin, which contains the following three components (A), (B), and (C) as essential components. (A) An epoxy resin consisting of a bisphenol A epoxy resin, a bisphenol AD epoxy resin, or a mixture thereof. (B) 0.2 to 0.6 mol of at least one of butyl glycidyl ether, phenyl glycidyl ether, o-cresyl glycidyl ether, and ethylhexyl glycidyl ether per 1 mol of the condensate of m-xylene diamine and epichlorohydrin. Modified polyamine with reactive addition in proportion. (C) Inorganic pigment.