JP2886916B2 - One-part thermosetting resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resin for highly corrosion-resistant paint which adheres to various materials.

(Prior art) Epoxy resins obtained by the reaction of a compound having a phenolic OH group with epihalogenohydrin have a highly reactive epoxy group, and thus are cross-linked with isocyanates, amines, polyamides, dibasic acids, etc. Is widely used as a heat-curable resin. Further workability,
In order to improve various physical properties such as processability, corrosion resistance, and reactivity, a so-called blocked isocyanate-modified epoxy resin mixed with block urethane is used. Among them, the one-component thermosetting resin in which block urethane is mixed with a modified polymer epoxy resin polymerized with a polyfunctional amine is at a relatively good level in terms of performance, but has corrosion resistance,
Moisture resistance was insufficient.

(Problems to be Solved by the Invention) The object of the present invention is to provide good adhesion to various materials, corrosion resistance,
An object of the present invention is to provide a coating resin having excellent moisture resistance.

(Means for Solving the Problems) As a means for solving these problems, the present invention uses block isocyanate as a crosslinking agent in a modified polymer epoxy resin obtained by adding a monoisocyanate to an amine-modified epoxy resin. As a result, the present inventors have found that a high corrosion resistance and high moisture resistance resin having good workability can be obtained without deteriorating various physical properties.

That is, the present invention relates to a polyfunctional amine having an epoxy equivalent of 400 to 3000 and having 1.0 or more polyfunctional epoxy resin having 1.0 or more polyfunctional epoxy resin having two or more glycidyl groups in one molecule.
(8) 95-70 parts (solid content ratio) of a coating resin (A) obtained by reacting a monoisocyanate with a modified epoxy resin polymerized by adding an active hydrogen equivalent to a polymer, and 5-30 parts of a blocked isocyanate (B) ( (Solid content ratio).

The epoxy resin used in the present invention is bisphenol A
Type epoxy resin, bisphenol F type epoxy resin, novolac glycidyl ether, glycidyl hexahydrophthalate, glycidyl dimer, tetraglycidylaminodiphenylmethane, 3,4-epoxy 6-methylcyclohexylmethyl carboxylate,
There are triglycidyl isocyanurate, 3,4-epoxycyclohexylmethyl carboxylate, propylene glycol diglycidyl ether and the like, preferably a bisphenol A type epoxy resin, and the epoxy equivalent is 400 to 3000. When the epoxy equivalent is less than 400, the obtained resin composition has poor corrosion resistance, and when the epoxy equivalent exceeds 3000, the processability is deteriorated, which is not preferable.

The polyfunctional amine used in the present invention is an amine having two or more active hydrogens in one molecule, such as isopropanolamine, monopropanolamine, monobutanolamine,
Diethylenetriamine, ethylenediamine, butylamine, propylamine, isophoronediamine, xylenediamine, diaminodiphenylmethane, diaminosulfone, octylamine, metaphenylenediamine, butylamine, amylamine, hexylamine, octylamine, nonylamine, decylamine, triethylenetetramine, tetraethylenepentamine , Diethylaminopropylamine, n-aminoethylpiperazine, mensendiamine, diaminodiphenylsulfone and the like.

When the production equivalent ratio of the modified epoxy resin in the present invention is 1.0 equivalent of the epoxy resin and the amine active hydrogen equivalent is less than 1.1, the obtained coating resin is excessively polymerized and gels. On the other hand, when the amine active hydrogen equivalent exceeds 1.8, the water resistance and the like deteriorate, and it cannot be used. From the above points, it is preferable that the amine active hydrogen equivalent is in the range of 1.1 to 1.8 with respect to the resin having an epoxy equivalent of 1.0.

Examples of the monoisocyanate used in the present invention include an aliphatic monoisocyanate obtained by reacting phosgene with an aliphatic monoamine and an aromatic monoisocyanate obtained by reacting phosgene with an aromatic monoamine. Further, one obtained by reacting one NCO group of the following diisocyanate compound with the following OH compound may be used.

Examples of the diisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate, lysine diisocyanate, and sulfonyl diisocyanate. And the like.

Examples of the OH compound include isopropyl alcohol, butyl alcohol, methyl alcohol, ethyl alcohol, propyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, iso-amyl alcohol, hexyl alcohol, 2-ethylhexanol, and heptyl alcohol. , Octyl alcohol, caprylic alcohol, nonyl alcohol, decyl alcohol, aliphatic saturated alcohols such as benzyl alcohol, aromatic alcohols such as cinamyl alcohol,
Alternatively, an alicyclic alcohol, cyclopentanol, cyclohexanol and the like can be mentioned.

Further, the amount of the monoisocyanate reaction added is preferably 0.7 to 2.0 times equivalent to the active hydrogen equivalent of the amine in the resin. Corrosion resistance, moisture resistance,
Performance such as secondary adhesion and workability is improved.

The blocked isocyanate used in the present invention means that the isocyanate group having a strong activity of the isocyanate compound is temporarily protected with an appropriate compound to make the isocyanate group inactive, and the blocking agent is dissociated by heating to easily regenerate the activity of the isocyanate. Things.

As the isocyanate compound used for the blocking agent, hexamethylene diisocyanate, aliphatic isocyanates such as trimethylhexamethylene diisocyanate, xylylene diisocyanate, 2,4-tolylene diisocyanate, aromatic diisocyanates such as 2,6-tolylene diisocyanate or Representative examples thereof include alicyclic diisocyanates such as isophorone diisocyanate, and further, a mixture of these diisocyanates and a multimer.

Further, a prepolymer having an NCO group at a terminal obtained by reacting these isocyanate compounds with an active hydrogen compound is exemplified. The prepolymer can be obtained by reacting the following active hydrogen compound with the isocyanate compound in a state where the NCO group is excessive. Active hydrogen compounds used to produce this prepolymer include, for example, ethylene glycol, propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, Dihydric alcohols such as neopentyl glycol, hydroxypivalate, triethylene glycol, xylylene glycol, 1,4-butylene glycol, and the like, for example, glycerin, trimethylolethane, trimethylolpropane, 1,2,6-hexanetriol, Low molecular weight polyols such as pentaerythritol; polyether polyols such as propylene oxide or ethylene oxide adducts of the above polyols; Polymeric polyols, such as such as those that fatty degeneration mentioned in making the polyester polyol obtained by reacting a Nsan. These polyols may be used alone or as a mixture.

These blocked isocyanates can be obtained by reacting these isocyanate compounds with the following blocking agents by a known method. As the blocking agent used in this reaction, for example, any of phenol-based, lactam-based, active methylene-based, acid amide-based, imide-based, oxime-based, or sulfite-based blocking agents can be used. , Oxime, lactam and imine blocking agents are advantageously used. The following are specific examples of the blocking agent.

Phenol-based blocking agents include phenol, cresol, xylenol, nitrophenol, chlorophenol, ethylphenol, p-hydroxydiphenyl,
t-butylphenol, o-isopropylphenol,
o-sec-butylphenol, p-nonylphenol,
pt-octylphenol, hydroxybenzoic acid, hydroxybenzoic acid ester and the like.

Lactam blocking agents such as ε-caprolactam,
δ-palerolactam, γ-butyrolactam, β-propiolactam and the like.

Examples of the oxime-based blocking agent include formamidoxime, acetoaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, and cyclohexanone oxime.

Examples of imine-based blocking agents include ethyleneimine and propyleneimine.

The above blocking reaction is known in a solvent having no active hydrogen (eg, an aromatic solvent such as xylene or toluene, a petroleum solvent such as Solvesso, or a ketone such as methyl ethyl ketone, cyclohexanone, or methyl isobutyl ketone) or a solvent-free solvent. Is performed in the following manner. In the reaction, a known catalyst such as a tertiary amine or an organic metal may be used.

The amount of the blocked isocyanate (B) added is 5 to 30 parts by weight based on 100 parts of the modified epoxy and monoisocyanate adducts (A).

In the present invention, to produce a modified epoxy resin,
An epoxy resin having an epoxy equivalent of 400 to 3000 is dissolved in a solvent, a polyfunctional amine is added, and the mixture is reacted at 70 to 150 ° C. for 4 to 10 hours to polymerize.

Thereafter, monoisocyanate is added, and the mixture is reacted at 50 to 90 ° C. for 4 to 10 hours, diluted to an appropriate viscosity with a solvent, and blocked isocyanate is added to obtain a resin solution. However, the reaction is performed in an N ₂ atmosphere. Solvents include toluene (hereinafter abbreviated as TOL), cyclohexanone, and methyl ethyl ketone (hereinafter, referred to as TOL).
MEK), isopropyl alcohol (hereinafter abbreviated as IPA), xylene (hereinafter abbreviated as XY), propylene glycol monomethyl ether acetate (hereinafter abbreviated as PMA)
And the like).

When preparing a paint using the one-part thermosetting resin composition of the present invention, rust-preventive pigments, extender pigments, and various additives,
A leveling agent may be added to form a coating by a known method such as a disper, a sand mill, a ball mill or the like.

As a coating method, a general method such as brush coating, spray coating, and various coater coatings can be used, and applicable materials are various metal materials such as a cold-rolled steel sheet, a galvanized steel sheet, an alloyed galvanized steel sheet, and chromium. Plated steel sheet, aluminum plated steel sheet, tin plated steel sheet, lead plated steel sheet,
Examples include nickel-plated steel sheets, aluminum sheets, titanium sheets, and stainless steel sheets. The resin composition of the present invention is applied directly or after performing a pre-coating treatment.

The one-part thermosetting resin of the present invention thus obtained is applied to a substrate and heated to form a blocking agent (B).
Dissociates to regenerate the NCO group, and this regenerated NCO group
A cured coating film obtained by reacting with OH is obtained.

The heating temperature depends on the type of blocking agent, etc.
At ~ 350 ° C, the time is from 20 seconds to tens of minutes.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples.

In addition, the monoisocyanate used below is 2,
NCO content obtained by reacting octanol with 4-tolylene diisocyanate is 10%, and blocked isocyanate (B) is obtained by reacting 2,4-tolylene diisocyanate with a propylene oxide adduct having a molecular weight of 2,000, Blocked with ε-caprolactam.

Example 1. Bisphenol A type epoxy resin having an epoxy equivalent of 2000
Add 800 parts of xylene and 400 parts of cyclohexanone to 1200 parts, dissolve and reflux dehydrate with xylene, then isopropanolamine
Add 36 parts and perform addition reaction at 100 ° C. After the addition reaction, the mixture was cooled to 60 ° C. or less, 145 parts of monoisocyanate was added, and the mixture was reacted at 70 ° C. for 5 hours. Block isocyanate (B)
278 parts were added to obtain a resin solution having a solid content of 40%.

Example 2. Bisphenol A type epoxy resin 1 having an epoxy equivalent of 900
To 200 parts, 800 parts of xylene and 400 parts of cyclohexanone are added and dissolved. After refluxing and dehydrating with xylene, 114 parts of benzylamine is added, and an addition reaction is performed at 100 ° C. for 5 hours. After the addition reaction, the mixture was cooled to 60 ° C. or lower, 300 parts of monoisocyanate was added and reacted at 70 ° C. for 5 hours, and 483 parts of IPA, 483 parts of propylene glycol monomethyl ether acetate, and 483 parts of MEK were added to obtain a resin solution (A). 307 parts of blocked isocyanate (B) was added to this solution to obtain a resin solution having a solid content of 40%.

Example 3. Bisphenol A type epoxy resin having an epoxy equivalent of 2800
Add 1200 parts of xylene and 400 parts of cyclohexanone to 1200 parts, dissolve and reflux dehydrate with toluene.
Add 21 parts and react at 100 ° C for 5 hours. 60 after addition reaction
Cool to below ℃, add 100 parts of monoisocyanate to 70 ℃
And 336 parts of IPA, 336 parts of propylene glycol monomethyl ether acetate, and 336 parts of MEK were added to obtain a resin solution (A). 307 parts of blocked isocyanate (B) was added to this solution to obtain a resin solution having a solid content of 40%.

Example 4. Bisphenol A type epoxy resin 1 having an epoxy equivalent of 500
Add 800 parts of xylene and 400 parts of cyclohexanone to 200 parts, dissolve and reflux dehydrate with xylene, and then isopropanolamine.
86 parts and 23.0 parts of ethylenediamine are added and an addition reaction is carried out at 100 ° C. for 5 hours.

350 parts of monoisocyanate was added and reacted at 70 ° C. for 5 hours. Resin solution (A) was added with 512 parts of IPA, 512 parts of propylene glycol monomethyl ether acetate and 512 parts of MEK.
I got The blocked isocyanate (B) 335 is added to this solution.
To obtain a resin solution having a solid content of 40%.

Example 5. Bisphenol A type epoxy resin having an epoxy equivalent of 2000
To 1200 parts, 800 parts of xylene and 400 parts of cyclohexanone are added and dissolved. The mixture is refluxed and dehydrated with xylene, and 27 parts of isopropanolamine is added, followed by an addition reaction at 100 ° C. for 5 hours. After addition reaction 6
Cool to 0 ° C or less, add 60 parts of monoisocyanate and add 70 parts
The mixture was reacted at 5 ° C. for 5 hours, and 315 parts of propylene glycol monomethyl ether acetate, 315 parts of IPA and 315 parts of MEK were added to obtain a resin solution (A). 285 parts of blocked isocyanate (B) was added to this solution to obtain a resin solution having a solid content of 40%.

Example 6. Bisphenol A type epoxy resin having an epoxy equivalent of 2000
800 parts of xylene and 400 parts of cyclohexanone are added and dissolved in 1200 parts, and the mixture is refluxed and dehydrated with xylene. Then, 38.3 parts of isopropanolamine is added, and an addition reaction is performed at 100 ° C. for 5 hours. After the addition reaction, the mixture was cooled to 60 ° C. or lower, 170 parts of monoisocyanate was added and reacted at 70 ° C. for 5 hours, and 475 parts of propylene glycol monomethyl ether acetate, 475 parts of IPA, and 475 parts of MEK were added to obtain a resin solution (A). 285 parts of blocked isocyanate (B) was added to this solution to obtain a resin solution having a solid content of 40%.

Comparative Example 1. Bisphenol A type epoxy resin with an epoxy equivalent of 2000
To 1200 parts, 800 parts of xylene and 400 parts of cyclohexanone are added and dissolved. The mixture is dehydrated by refluxing with xylene, 23.6 parts of isopropanolamine is added, and an addition reaction is performed at 100 ° C. It gelled after 30 minutes.

Comparative Example 2. Bisphenol A type epoxy resin 12 having an epoxy equivalent of 2000
To 800 parts, 800 parts of xylene and 400 parts of cyclohexanone were added and dissolved, and refluxed and dehydrated with toluene.
Add 2.8 parts and perform addition reaction at 100 ° C for 5 hours. 60 after addition reaction
C. and cooled to below 70
The mixture was reacted at 5 ° C. for 5 hours, and 424 parts of propylene glycol monomethyl ether acetate, 424 parts of IPA and 424 parts of MEK were added to obtain a resin solution (A). To this solution, 310 parts of blocked isocyanate (B) was added to obtain a resin solution having a solid content of 40%.

Comparative Example 3. Bisphenol A type epoxy resin having an epoxy equivalent of 2000
To 1200 parts, 800 parts of xylene and 400 parts of cyclohexanone are added and dissolved. The mixture is refluxed and dehydrated with xylene, and 36 parts of isopropanolamine is added, followed by addition reaction at 100 ° C. for 5 hours. After addition reaction 6
After cooling to 0 ° C. or lower, 218 parts of IPA, 416 parts of propylene glycol monoethyl ether acetate, and 218 parts of MEK were added without adding a monoisocyanate to obtain a resin solution.

(A) Block isocyanate (B) 264 in this solution
A resin solution having a solid content of 40% was obtained.

Using the resin solution obtained in each of Examples and Comparative Examples, 64 parts of titanium oxide and 16 parts of strontium chromate are added to 200 parts of an epoxy resin as a pigment, and the mixture is sufficiently kneaded using three rolls to prepare a primer coating material.

Material Zinc phosphate treated steel sheet Primer baking conditions 210 ° C × 45 seconds Primer film thickness 6μ Topcoat baking conditions 210 ° C × 60 seconds Topcoat film thickness 15μ Note that a commercially available paint for coil coating was used. Table 1 shows the test results.

(Effects of the Invention) According to the present invention, improvements in corrosion resistance and moisture resistance, which have not been achieved by the prior art, are achieved. Therefore, the present invention is suitable for the production of a one-part thermosetting resin composition for applications requiring corrosion resistance and moisture resistance.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 175/00-175/12 C08G 18/58

Claims (1)

(57) [Claims] 1. An epoxy resin having an epoxy equivalent of from 400 to 3000 and having 1.0 or more of a polyfunctional epoxy resin having two or more glycidyl groups in one molecule, and adding 1.1 to 1.8 active hydrogen equivalents of a polyfunctional amine to a high molecular weight resin. Coating resin (A) prepared by reacting monoisocyanate with molecularly modified modified epoxy resin
A one-part thermosetting resin composition comprising 95 to 70 parts (solid content ratio) and 5 to 30 parts (solid content ratio) of blocked isocyanate (B).