JP7013699B2 - Urethane modified epoxy resin and one-component lacquer type paint - Google Patents

Description

The present invention relates to a urethane-modified epoxy resin and a one-component / lacquer type paint.

The bisphenol A type epoxy resin obtained by reacting bisphenol A with epichlorohydrin or the like has excellent rust resistance, adhesion, chemical resistance, etc. due to the reactivity of the epoxy group and the hydroxyl group in the resin. Therefore, it is widely used as a resin for paints.

By the way, since an epoxy resin generally does not have self-curing property, when an epoxy resin paint is cured at room temperature, it is used as a two-component reaction type paint in which a curing agent such as polyamine or polyamide is mixed in the paint.

However, the two-component reaction type paint must be mixed with a curing agent immediately before it is applied to the base material, which is inconvenient to handle and is subject to various practical restrictions in terms of pot life (pot life). Cheap. Therefore, there has been an urgent need for a one-component, lacquer-type paint resin that can be dried at room temperature without adding a curing agent while maintaining the adhesiveness and rust prevention properties of an epoxy resin.

As a solution to this problem, for example, a paint resin containing a urethane-modified epoxy resin obtained by reacting an epoxy resin obtained from a bisphenol type epoxy resin and amines with a polyisocyanate compound is known (Patent Documents). 1). Further, as a resin for a lacquer type paint having excellent long-term rust resistance and corrosion resistance while maintaining high hardness, it can be obtained by reacting a bisphenol type epoxy resin, a secondary alkanolamine and an alkylamine of C8 or higher. Amine-modified epoxy resin and a polyisocyanate compound reacted with each other are also known (Patent Document 2).

By the way, in recent years, one-component lacquer type paints have been modified to achieve high solidification (high solidification) by reducing the amount of solvent in order to further reduce the environmental load while maintaining various properties such as rust prevention of the coating film. The development of epoxy resin has been desired.

Special Fair 6-89289 Gazette Japanese Unexamined Patent Publication No. 2010-235919

An object of the present invention is to solve the above-mentioned problems, and to provide a urethane-modified epoxy resin which is excellent in rust prevention, primary adhesion and water resistance, and can realize high solidification of a coating material.

The present inventors used an epoxy resin having a predetermined epoxy group concentration and a predetermined amount of alkanolamines as raw materials, and reacted an amine-modified epoxy resin having a relatively increased amine value with polyisocyanate. It has been found that the above-mentioned problems can be solved by the urethane-modified epoxy resin. That is, the present invention relates to the following urethane-modified epoxy resin and one-component / lacquer type paint.

1. 1. A reaction product of an amine-modified epoxy resin (A) composed of a bisphenol type epoxy resin ( a1) and amines (a2) (excluding diamines ), and polyisocyanates (B).
The epoxy group concentration of the component (a1) is 1.2 × 10 ^-3 to 4.5 × 10 ^-3 eq / g.
The component (a2) contains 0.1 to 50% by weight of alkanolamines (a2-1).
The amine value of the component (A) is 40 to 90 mgKOH / g, and the component has an amine value of 40 to 90 mgKOH / g.
(A1) 44.5 to 100% by weight of the component is a bisphenol epoxy resin having 4 to 6 hydroxyl groups per molecule when the epoxy group is ring-opened .
Urethane modified epoxy resin.

2. 2. Item 1 above, wherein the ratio of the component (a1) and the component (a2) used is {the number of epoxy groups of the component (a1)} / {the number of active hydrogens of the amino group of the component (a2)} = 100/120 to 100/80. Urethane modified epoxy resin.

3. 3. The urethane-modified epoxy resin according to Item 1 or 2, wherein the ratio of the component (A) and the component (B) used is {the number of isocyanate groups in (B) / the number of hydroxyl groups in (A)} is 0.001 to 0.40. ..

4. A one-component, lacquer-type paint using the urethane-modified epoxy resin according to any one of Items 1 to 3.

5. The one-component / lacquer type paint of item 4 above, wherein the non-volatile content of the paint is 50% by weight or more.

The urethane-modified epoxy resin of the present invention is coated by using an epoxy resin having a predetermined number of epoxy groups and an amine-modified epoxy resin having a relatively high amine value using a predetermined amount of alkanolamines as raw materials. While maintaining the hardness and flexibility of the above, it is excellent in rust resistance, primary adhesion and water resistance, and can realize high solidification of paint. Further, the one-component / lacquer type paint obtained by using the urethane-modified epoxy resin of the present invention is suitable from the viewpoint of environmental suitability because the solvent content can be reduced.

The urethane-modified epoxy resin of the present invention is an amine-modified epoxy resin composed of a bisphenol type epoxy resin (a1) (hereinafter referred to as (a1) component) and predetermined amines (a2) (hereinafter referred to as (a2) component). A) (hereinafter referred to as the component (A)) and a reaction product of the polyisocyanate (B) (hereinafter referred to as the component (B)).

The component (a1) is a bisphenol type epoxy resin .

As the component (a 1 ), various known bisphenol type epoxy resins can be used without particular limitation. For example, a reaction product of bisphenols and haloepoxides such as epichlorohydrin or β-methylepichlorohydrin can be mentioned. Examples of bisphenols include a reaction product of phenol or 2,6-dihalophenol with aldehydes or ketones such as formaldehyde, acetaldehyde, acetone, acetophenone, cyclohexanone, and benzophenone, and an oxidation reaction product of dihydroxyphenylsulfide with a peracid. In addition, an etherification reaction product of hydroquinones and the like can be mentioned. Specific examples of bisphenols include 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) and bis (4-hydroxyphenyl) methane (bisphenol F), which have adhesion to a substrate. From the viewpoint of rust resistance, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) is preferable. These (a 1 ) components are used alone or in combination of two or more as appropriate.

In the present invention, in order to obtain the component (A) having a predetermined amine value, the final coating film has good rust resistance, primary adhesion, water resistance, and high solidification. (A1) The epoxy group concentration of the component is an important parameter. The epoxy group concentration of the component (a1) is represented by the number of epoxy groups per gram in the component (a1). Hereinafter, the calculation method will be described by taking the component (a1-1) and the component (a1-2) as examples.

When one kind of the component (a1-1) is used, the epoxy group concentration of the component (a1) is calculated from (Equation 1) using the epoxy equivalent of the component (a1-1).

(Equation 1)

When a plurality of components (a1-1) are used, the epoxy group concentration of the component (a1) is calculated from (Equation 3). Here, the plurality of (a1-1) components are represented as (a1-1-1), (a1-1-2), ..., (A1-1-n).

(Equation 3)

The epoxy group concentration of the component (a1) is usually 1.2 × 10 ^-3 to 4.5 × 10 ^-3 eq / g. When the epoxy group concentration is less than 1.2 × 10 ^-3 eq / g, the amine value of the component (A) is lowered, and the rust preventive property of the coating film is lowered. Further, when the epoxy group concentration exceeds 4.5 × 10 ^-3 eq / g, the amine value of the component (A) becomes high, and the water resistance and rust resistance of the coating film are lowered. From these viewpoints, it is preferably 1.5 × 10 ^-3 to 4 × 10 ^-3 eq / g.
Assuming that the epoxy group concentration of the component (a1) satisfies the above range, the individual epoxy resins belonging to the component (a1) (for example, the component (a1-1), the component (a1-2), (a1-2) component, ( The epoxy group concentration of a1-1-1) component, etc.) can be freely used even if it is out of the above range.

The component (a2) contains amines (however, diamines are excluded) containing a predetermined amount of alkanolamines (a2-1) (hereinafter referred to as (a2-1) component) from the viewpoint of adhesion to the base material. Is.

As the component (a2-1), various known alkanolamines can be used without particular limitation. For example, primary alkanolamines such as monoethanolamine, monoisopropanolamine; diethanolamine, diisopropanolamine, di-2-hydroxybutylamine, N-methylethanolamine, N-ethylethanolamine, N-benzylethanolamine and the like. Examples thereof include tertiary alkanolamines such as secondary alkanolamines, triethanolamines, and tripropanolamines, which may be used alone or in combination of two or more. Among these, primary alkanolamines and / or secondary alkanolamines are preferable, and monoethanolamine and / or diethanolamine are more preferable, from the viewpoint of adhesion to the substrate.

The content of the component (a2-1) is 0.1 to 17.8 % by weight in the component (a2). If the content is less than 0.1% by weight, the primary adhesion and rust prevention of the coating film are inferior, and if it exceeds 17.8 % by weight, the water adhesion and rust prevention of the coating film are inferior.

The component (a2) may include non-alkanolamines (a2-2) (hereinafter referred to as the component (a2-2)). The component (a2-2) is not particularly limited, and for example, ethylamine, propylamine, butylamine, hexylamine, octylamine, laurylamine, stearylamine, n-palmitylamine, oleylamine, 2-ethylhexylamine and the like. Primary aliphatic monoamines ; Secondary aliphatic monoamines such as diethylamine, dipropylamine, dibutylamine; Aromatic amines such as toluidine, xylidine, kumidine (isopropylaniline), hexylaniline, nonylaniline, dodecylaniline; cyclopentylamine , Alicyclic amines such as cyclohexylamine and norbonylamine; aromatic nucleus-substituted aliphatic amines such as benzylamine and phenethylamine can be mentioned. These amines may be used alone or in combination of two or more as appropriate. Among these, aliphatic amines are preferable, and primary aliphatic monoamines and / or secondary aliphatic monoamines are more preferable from the viewpoint of water resistance and adhesion of the coating film.

The proportion of the component (a2-2) used is not particularly limited, but is about 50 to 99.9% by weight, preferably about 70 to 95% by weight. If it is less than 50% by weight, the water-based adhesion and rust-preventive property of the coating film are inferior, and if the content exceeds 99.9% by weight, the primary adhesion and rust-proofing property of the coating film are inferior.

As for the usage ratio of the component (a1) and the component (a2), {the number of epoxy groups of the component (a1)} / {the number of active hydrogens of the amino group of the component (a2)} is about 100/120 to 100/80, preferably about 100/120 to 100/80. It is about 100/110 to 100/90, more preferably about 100/105 to 100/95. Within this range, the component (a1) and the component (a2) are consumed, and the component (A) having a predetermined amine value can be easily obtained.

The number of epoxy groups of the component (a1) is a value obtained by dividing the charged weight of the component (a1) by the epoxy equivalent of the component (a1). (A1) When there are a plurality of components, the number of epoxy groups is calculated from (Equation 4).

(Equation 4)

The number of active hydrogens in the amino group of the component (a2) is a value obtained by dividing the charged weight of the component (a2) by the amine equivalent of the component (a2). (A2) When there are a plurality of components, the number of active hydrogens is calculated from (Equation 5).

(Equation 5)

The component (A) can be produced by reacting the component (a1 ) , the component (a2-1), and if necessary, the component ( a2-2) under the following conditions. The production conditions are not particularly limited, but the reaction temperature is usually about 50 to 250 ° C, preferably about 80 to 150 ° C. The reaction time is not particularly limited because it depends on the reaction temperature, but is usually about 3 to 10 hours, preferably 3 to 6 hours from the viewpoint of production efficiency.

As the physical properties of the component (A), the amine value is important in terms of making the paint high solid and satisfying the rust preventive property, the primary adhesive property and the water resistant adhesive property of the coating film. The amine value is measured according to JIS K-7237. The amine value of the component (A) is 40 to 90 mgKOH / g, preferably 50 to 85 mgKOH / g, and more preferably 60 to 80 mgKOH / g. When the amine value is less than 40 mgKOH / g, the rust preventive property of the coating film tends to decrease, and when it exceeds 90 mgKOH / g, the water adhesion resistance of the coating film tends to decrease.

The component (B) is not particularly limited, and various known components can be used. For example, aromatic polyisocyanates, aliphatic polyisocyanates, alicyclic polyisocyanates and the like may be mentioned, and these may be used alone or in combination of two or more as appropriate.

Examples of aromatic polyisocyanates include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, and tetra. Examples thereof include alkyldiphenylmethane diisocyanate, 1,3-phenylenediocyanate, 1,4-phenylenediocyanate, tolylene diisocyanate, orthotoluidine diisocyanate, and polyphenylpolyisocyanate. These can be used in combination of two or more.

Examples of the aliphatic polyisocyanates include butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. .. These can be used in combination of two or more.

Examples of alicyclic polyisocyanates include cyclohexane-1,4-diisocyanate, xylylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methylcyclohexanediisocyanate, and isophorone diisocyanate. And so on. These can be used in combination of two or more.

In the production of the urethane-modified epoxy resin of the present invention, the amounts of the components (A) and (B) used are not particularly limited, but usually {the number of isocyanate groups of the component (B)} / {the number of hydroxyl groups of the component (A) } May be about 0.001 to 0.4, preferably about 0.005 to 0.3, and more preferably about 0.01 to 0.2. When it is 0.001 or more, the molecular weight of the obtained urethane-modified epoxy resin becomes moderately high, and it is suitable as a resin for a one-component / lacquer type paint that can be dried at room temperature. On the other hand, when it is 0.4 or less, excessive increase in molecular weight can be suppressed, which is suitable as a high solid type paint.

The number of hydroxyl groups of the component (A) is the total value of the number of hydroxyl groups of the component (a1) and the number of hydroxyl groups of the component (a2).

(I): The number of hydroxyl groups of the component (a1) is calculated by multiplying the charged molar amount of the component (a1) by the number of hydroxyl groups per molecule including the hydroxyl group generated when the epoxy group of the component (a1) is opened. can. When the component (a1) contains a plurality of components, the number of hydroxyl groups of the component (a1) is the total number of hydroxyl groups of each component.

(Ii): The number of hydroxyl groups of the component (a2) can be calculated by multiplying the charged molar amount of the component (a2) by the number of hydroxyl groups per molecule of the component (a2). When the component (a2) contains a plurality of components, the number of hydroxyl groups of the component (a2) is the total number of hydroxyl groups of each component.

The number of isocyanate groups of the component (B) is a value obtained by multiplying the charged molar amount of the component (B) by the number of isocyanate groups per molecule of the component (B). When there are a plurality of components (B), the number of isocyanate groups is the total number of isocyanate groups of each component.

The reaction conditions of the component (A) and the component (B) are not particularly limited, but the reaction temperature is usually about 20 to 200 ° C, preferably about 50 to 150 ° C. The reaction time is usually about 3 to 10 hours, preferably about 3 to 6 hours.

A solvent can be used in the reaction. For example, it has hydrocarbons such as toluene and xylene, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, and active hydrogen such as cellosolve acetate such as methyl cellosolve acetate and cellosolve acetate. There are some that do not, and each can be used alone or in combination of two or more as appropriate. After the urethane-modified epoxy resin of the present invention is produced, as a diluting solvent, a solvent having active hydrogen such as cellosolves such as methyl cellosolve and ethyl cellosolve; alcohols such as isopropyl alcohol and n-butyl alcohol may be used. Can be used without.

The weight average molecular weight (polystyrene equivalent value by gel permeation chromatography) of the urethane-modified epoxy resin of the present invention is not particularly limited, and is preferably in the range of about 10,000 to 100,000, more preferably 20,000. It is about 50,000. By setting the weight average molecular weight to 10,000 or more, a resin suitable for a one-component / lacquer type paint having high rust resistance and water adhesion for a long period of time can be obtained, and the weight average molecular weight should be 100,000 or less. As a result, it is easy to obtain a resin suitable for a high solid type paint that suppresses high viscosity.

The solid content concentration of the urethane-modified epoxy resin of the present invention is not particularly limited and may be appropriately determined in consideration of the viscosity and the like when made into a paint, but is usually about 30 to 80% by weight. .. Further, from the viewpoint of handleability of the obtained paint, the viscosity of the resin solution is adjusted to about R to Z ₇ (Gardner method, 25 ° C.) before use.

A one-component lacquer type paint (hereinafter referred to as the present paint) using the modified epoxy resin for urethane of the present invention will be described below. This paint can be used as a paint for normal temperature drying, and is also suitable as a forced drying paint, a baking paint, and the like. Further, the present paint is not particularly limited to the object to be coated and the intended use, and can be widely applied, but is suitable for undercoating in consideration of performance such as rust prevention and adhesion of the coating film.

In the preparation of this paint, coloring pigments such as carbon black and titanium oxide, moisture-resistant pigments such as talc, calcium carbonate and barium sulfate, and rust-preventive pigments such as aluminum phosphomolybate and zinc phosphate can be appropriately blended. .. In addition, a curing agent such as a melamine resin, a urea resin, an isocyanate, or a blocked isocyanate, various known solvents, and other additives may be appropriately added to the present paint, if necessary. When the present paint is made into a high solid, the non-volatile content is usually 50% by weight or more, preferably about 55 to 80% by weight, and more preferably 60 to 80% by weight.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to these examples. Further, in each Example and Comparative Example, parts or% are shown by weight.

Example 1
In a reaction vessel equipped with a stirrer, cooler, thermometer and nitrogen gas inlet tube,
As the component (a 1 ), jER1001 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 475 g / eq) 150 g, YD-128 (manufactured by Nippon Steel & Sumitomo Metal Corporation, epoxy equivalent 189 g / eq) 52 g were charged, and the component (a 1) was added. Prepared. The epoxy group concentration of the component (a1) was 2.9 × 10 ^-3 eq / g.
Next, 10 g of diethanolamine and 0.1 g of monoethanolamine were charged as the component (a2-1), and 28 g of stearylamine and 18.5 g of 2-ethylhexylamine and 128 g of xylene were charged as the components (a2-2). The reaction at ° C. for 5 hours gave an amine-modified epoxy resin (A1) having an amine value of 70 mgKOH / g.
Next, 8.0 g of isophorone diisocyanate and 90 g of cyclohexanone were charged into the reaction vessel as the components (B), and these were reacted at 100 ° C. for 4 hours under a nitrogen stream to obtain a urethane-modified epoxy resin. The weight average molecular weight of the obtained epoxy resin was measured under the following conditions and is shown in Table 1 (the same applies hereinafter).

[Weight average molecular weight of urethane-modified epoxy resin]
Equipment: HLC-8220 (manufactured by Tosoh Corporation)
Column: TSKgel α-2500 × 1, α-3000 × 1
Separation solvent: DMF (containing 5 mmol / kg of LiBr),
Flow rate: 1 ml / min
Temperature: 40 ° C
Standard: Polystyrene

Examples 2 to 5 , Comparative Examples 1 to 4
The composition shown in Table 1 was synthesized according to the same method as in Example 1 to obtain a urethane-modified epoxy resin.

(Preparation of various paints and test coating film)
Mixtures having the following compositions were kneaded with a paint shaker to prepare a one-component lacquer type paint. The obtained paint was applied onto a degreased dull steel sheet (SPCC-SD, 0.8 × 70 × 150 mm) with a bar coater so that the film thickness after drying was 25 μm, and forced drying (80 ° C. × 20). After minutes), the mixture was left at room temperature (20 ° C., 60% RH) for 6 days to prepare a test coating film, which was subjected to the following test.

(composition)
Each lacquer type paint resin obtained in Examples 1 to 5 and Comparative Examples 1 to 4 Titanium oxide 80 parts Carbon black 4 parts Precipitating barium sulfate 80 parts Aluminum phosphate rust preventive pigment 16 parts Xylene 35 parts Cyclohexanone 35 copies

(Evaluation test of coating film)
(1) Pencil hardness Complies with JIS K5600-5-4.

(2) Flexibility (bending test)
Apply each paint on a chin-free steel plate (0.3 x 120 x 200 mm) with a bar coater so that the film thickness after drying is 25 μm, and after forced drying (80 ° C x 20 minutes), room temperature (80 ° C x 20 minutes). It was left at 20 ° C. and 60% RH) for 6 days to obtain a test piece. Each test piece was bent with a vise and the presence or absence of cracks in the bent portion was confirmed. Flexibility was evaluated by the number of plates (chin-free steel plates) sandwiched between them (2T means that the plates to be sandwiched are bent by two plates and there is no cracking).

(3) Primary adhesion Performed according to JIS K5600-5-6, and after painting, 23 ° C., 50% R.M. H. The checkered adhesion when the test coating film cured for 6 days in the above environment was peeled off was evaluated as 100.

(4) Water Adhesion Resistance The test coating film soaked in warm water at 40 ° C. for 10 days was peeled off and evaluated as 100.

(5) Rust resistance Performed according to JIS K5600-7-9, and shown by the cellophane tape peeling width (mm) after 10 days and 20 days of the salt spray test.
The results of these evaluations are shown in Table 1.

In Table 1, the numerical values relating to the component (a1), the component (a2) and the component (B) all indicate the parts by weight charged. In addition, each symbol means the following.
jER1001 (manufactured by Mitsubishi Chemical Corporation, trade name "jER1001", epoxy equivalent 475 g / eq, number of hydroxyl groups per molecule when the epoxy group is opened: 4)
YD-128 (manufactured by Nippon Steel & Sumitomo Metal Corporation, trade name "Epototo YD-128", epoxy equivalent 189 g / eq, number of hydroxyl groups per molecule when the epoxy group is opened: 2)
YD-014 (manufactured by Nippon Steel & Sumitomo Metal Corporation, trade name "Epototo YD-014", epoxy equivalent 950 g / eq, number of hydroxyl groups per molecule when the epoxy group is opened: 6)
YDF-2001 (manufactured by Nippon Steel & Sumitomo Metal Corporation, trade name "Epototo YDF-2001", epoxy equivalent 470 g / eq, number of hydroxyl groups per molecule when the epoxy group is opened: 4)
YDF-170 (manufactured by Nippon Steel & Sumitomo Metal Corporation, trade name "Epototo YDF-170", epoxy equivalent 170 g / eq, number of hydroxyl groups per molecule when the epoxy group is opened: 2)
SA: Stearylamine (amine equivalent: 134.75, number of hydroxyl groups per molecule: 0)
DEA: Diethanolamine (amine equivalent: 105, number of hydroxyl groups per molecule: 2)
MEA: Monoethanolamine (amine equivalent: 30.5, number of hydroxyl groups per molecule: 1)
2EHA: 2-ethylhexylamine (amine equivalent: 64.6, number of hydroxyl groups per molecule: 0)
DBA: Dibutylamine (amine equivalent: 129.2, number of hydroxyl groups per molecule: 0)
IPDI: Isophorone diisocyanate (manufactured by Sumitomo Bayer Urethane Co., Ltd .: number of isocyanate groups per molecule: 2)
NV (%): Solid content concentration Mw: Weight average molecular weight Vis: Gardner viscosity (25 ° C)

Claims (5)

A reaction product of an amine-modified epoxy resin (A) composed of a bisphenol type epoxy resin (a1) and amines (a2) (excluding diamines), and polyisocyanates (B).
The epoxy group concentration of the component (a1) is 1.2 × 10 ^-3 to 4.5 × 10 ^-3 eq / g.
The component (a2) contains 0.1 to 17.8 % by weight of alkanolamines (a2-1).
The amine value of the component (A) is 40 to 90 mgKOH / g, and the component has an amine value of 40 to 90 mgKOH / g.
(A1) 44.5 to 100% by weight of the component is a bisphenol epoxy resin having 4 to 6 hydroxyl groups per molecule when the epoxy group is ring-opened.
Urethane modified epoxy resin. Claimed that the ratio of the component (a1) and the component (a2) used is {the number of epoxy groups of the component (a1)} / {the number of active hydrogens of the amino group of the component (a2)} = 100/120 to 100/80. Urethane modified epoxy resin of 1. The urethane-modified epoxy resin according to claim 1 or 2, wherein the ratio of the component (A) and the component (B) used is {number of isocyanate groups in (B) / number of hydroxyl groups in (A)} = 0.001 to 0.4. .. A one-component, lacquer-type paint containing the urethane-modified epoxy resin according to any one of claims 1 to 3. The one-component lacquer type paint according to claim 4, which has a non-volatile content of 50% by weight or more.