JPH04275318A - Thermosetting resin composition - Google Patents

Abstract

PURPOSE:To provide a new thermosetting resin composition excellent in mechanical properties, especially impact and chipping resistance and stretchability. CONSTITUTION:A thermosetting resin composition is composed of a polyamide resin having 80-600 active hydrogen equiv. or combination of an epoxy adduct of the aforementioned resin with a blocked isocyanate compound. Films of a thermosetting one-pack type urethane resin coating based on the thermosetting resin composition of this invention are excellent in mechanical properties such as impact and chipping resistance and stretchability in addition to excellent adhesion to substrates. The aforementioned resin composition can suitably be used for applications as undercoatings and intercoatings within a wide range of uses, including automotive applications.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to thermosetting resin compositions. More specifically, the present invention relates to a heat-curable resin composition suitable for use as an undercoat or intermediate coating, which has particularly excellent impact resistance, stretchability, and chipping resistance.

0002

BACKGROUND OF THE INVENTION Polyamide resins are synthesized from polybasic acids, polymerized fatty acids, natural fatty acids, and polyamines, so they have a chemically flexible structure and exhibit excellent impact resistance. Furthermore, epoxy adducts of the resin (polyamide adduct resin)
also has similar properties. Polyamide resins or epoxy adducts of these resins have traditionally been widely used as curing agents for epoxy resin paints, and this type of paint is increasingly being applied to not only steel structures but also parts of electrical products and various industrial products. . However, although these coatings exhibit excellent performance in terms of corrosion resistance and adhesion, they are hard, so impact resistance, elongation, and chipping resistance tend to decrease, and they are susceptible to mechanical damage. The problem is that it is easy.

0003

SUMMARY OF THE INVENTION An object of the present invention is to provide a new thermosetting resin composition which has excellent mechanical properties, particularly impact resistance, stretchability and chipping resistance.

0004

[Means for Solving the Problems] The present inventors have discovered that a coating film obtained by curing a polyamide resin or an epoxy adduct of the resin with a blocked isocyanate compound exhibits excellent mechanical properties, and has developed the present invention. Completed. That is, the present invention provides a thermosetting resin composition comprising a combination of a polyamide resin having an active hydrogen equivalent of 80 to 600 or an epoxy adduct of the resin and a blocked isocyanate compound.

[0005] The present invention will be explained in detail below. The polyamide resin used in the composition of the present invention is a polymer resin having an amide bond in its main chain and can be used without particular limitation as long as it has a low molecular weight of about 200 to 1000. For example, various polyamide resins that can be produced by condensing polybasic acids and polyamines can be used.

Examples of polybasic acids which are raw materials for the polyamide resin used in the present invention include phthalic anhydride, isophthalic acid, dimer acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, adipic acid,
Polybasic acids commonly used for polyester production such as sebacic acid and maleic anhydride or their acid anhydrides are
A species or a mixture of two or more kinds can be used.

[0007] Examples of polyamines that are raw materials for the polyamide resin used in the present invention include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, and tertiary amines. Specifically, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylpentamine, diaminodiphenylmethane, metaphenylenediamine, diaminodiphenylsulfone, metaxylenediamine, menthendiamine, isophoronediamine, N-
Examples include aminoethylpiperazine, bis(4-amino-3-methylcyclohexyl)methane, tris(dimethyl)aminomethylphenol, and the like. These can be used alone or in combination of two or more.

The epoxy adduct of polyamide resin used in the composition of the present invention is one in which an epoxy compound is reacted with the amide group at the terminal or main chain of the polyamide resin and added thereto. It is possible to use a resin in which a hydroxyl group side chain is formed in the polymer molecule. Examples of epoxy compounds used in the production of epoxy adducts in the present invention include epoxide compounds such as ethylene oxide, propylene oxide, and butylene oxide, bisphenol A epoxy resins, bisphenol F epoxy resins, alicyclic epoxy resins, and organic dibases. There are epoxy resins having diglycidyl esters of acids and hydantoin rings, and epoxy resins having one or more epoxy groups in the molecule can be used.

The polyamide resin or epoxy adduct of the resin used in the present invention has an active hydrogen equivalent (active hydrogen 1
The number of grams of resin (including equivalent weight) should be between 80 and 600, preferably between 90 and 550. If the active hydrogen equivalent is less than 80, a coating film with sufficient functional strength cannot be obtained due to the low molecular weight, and if it exceeds 600, the compatibility with the blocked isocyanate compound and curing reactivity will decrease, causing two-layer separation. This makes it difficult to form a uniform coating film.

As the polyamide resin or epoxy adduct of polyamide resin used in the composition of the present invention, for example, the following commercial products can be suitably used, but in the present invention, any epoxy adduct of polyamide resin can be used. Any material can be used as appropriate without particular limitation. Versamide 100, Versamide 115, Versamide 12
5. Versamide 140, Versamide 280 [manufactured by Henkel Hakusui Co., Ltd.], Tomide 410, Tomide 215, Tomide 21
3A, Tomide 225, Tomide 437 [manufactured by Fuji Chemical Industry Co., Ltd.], Sunmide 300, Sunmide 305, Sunmide 31
5. Sanmide X-2700 [manufactured by Sanwa Chemical Industry Co., Ltd.]
All of these epoxy adducts of polyamide resins are in liquid form, but they can be used as they are, or in the case of high viscosity, they can be diluted with a suitable solvent as needed and used as a solution.

The blocked isocyanate compound used in the present invention is a polyisocyanate compound whose isocyanate groups are made temporarily inactive at room temperature using a blocking agent. The activity of the isocyanate groups can be regenerated by removing the blocking agent by heating them above their inherent dissociation temperature. The thus obtained blocked isocyanate compound can remain stable unless heated, and is combined with an epoxy adduct of polyamide resin to obtain a heat-curable one-component polyurethane resin composition.

[0012] As the polyisocyanate compound used in the composition of the present invention, both aliphatic type and aromatic type may be used, such as hexamethylene diisocyanate,
In addition to isophorone diisocyanate, tolylene diisocyanate, m-xylylene diisocyanate, dimers and trimers thereof, reaction products of these polyisocyanate compounds with water, polyhydric alcohols such as ethylene glycol, propylene glycol, and trimethylolpropane. These compounds each have two or three isocyanate groups per molecule. Examples of blocking agents for the polyisocyanate used in the composition of the present invention include phenol, cresol,
Known blocking agents such as aromatic amines, tertiary alcohols, lactams, and oximes can be used as appropriate.

Examples of the blocked isocyanate compound used in the present invention include Desmodur BL-3175 (manufactured by Bayer) and Coronate 2, which are commercially available.
507, Coronate 2515 [Japan Polyurethane Industries (
Co., Ltd.], Takenate B-815N, Takenate 820
NSU, Takenate B-842N [Takeda Pharmaceutical Co., Ltd.
Aliphatic isocyanates such as Desmodur BL
-1260A, Desmodule BL-1185A (manufactured by Bayer), Takenate B-800, Takenate B-8
There are aromatic isocyanates such as No. 30 [manufactured by Takeda Pharmaceutical Co., Ltd.], which can be used alone or as a mixture of two or more thereof. The amount of the blocked isocyanate compound to be used is such that the isocyanate group of the polyfunctional isocyanate compound is 0.5 to 2.0 equivalents per equivalent of active hydrogen contained in the epoxy adduct of the polyamide resin, preferably It is desirable that the proportion be 0.7 to 1.5 equivalents.

In the present invention, the composition of the present invention obtained by mixing an epoxy adduct of a polyamide resin or a polyamide resin and a blocked isocyanate compound is applied to a surface to be coated, and then the dissociation inherent to the blocked isocyanate compound used is applied. By heating above this temperature, both of them undergo a curing reaction, and a coating film consisting of an addition product containing a urea bond can be obtained.

[0015] In order to prepare a paint using the heat-curable resin composition of the present invention, for example, based on an epoxy adduct of polyamide resin, known coloring pigments,
Extender pigments, antirust pigments, organic solvents, additives, and the like can be blended, but the composition is not limited to these, and a wide variety of raw materials commonly used for paints can be used.

Coloring pigments used in the composition of the present invention include:
For example, titanium oxide, Bengara, chrome yellow, carbon black, azo pigments, phthalocyanine, etc. can be used. Extender pigments used in the composition of the present invention include:
For example, kaolin, barium sulfate, calcium carbonate, talc, silica, alumina, hydrated alumina, hydrated magnesium, mica, barium carbonate, zirconia, silicon nitrogen,
Boron nitride, aluminum nitride, clay, etc. can be used.

[0017] As the rust-preventing pigment used in the composition of the present invention,
For example, strontium chromate, calcium chromate,
Zinc chromate, barium chromate, lead chromate, etc. can be used. Examples of organic solvents used in the composition of the present invention include hydrocarbon-based, ester-based, ketone-based,
Alcohol-based solvents, cellosolve-based solvents, and the like can be used, but the solvent is not limited to these, and a wide variety of solvents commonly used for paints can be used.

Examples of additives that can be used in the composition of the present invention include antifoaming agents, surface tension regulators, pigment dispersants, and anti-sag agents. When applying the heat-curable resin composition of the present invention to a paint, a polyamide resin or an epoxy adduct of a polyamide resin is used as a dispersion base material, a pigment and a solvent are mixed therein, and the particle size is dispersed to 15 μm or less. ,
Although the blocked isocyanate compound can be uniformly mixed to form a paint, the method is not limited to this method.

[0019]

[Examples] The present invention will be specifically explained below using Examples and Comparative Examples. All parts in the examples are parts by weight. Examples 1 to 4 and Comparative Examples 1 and 2 Clear paints of Examples 1 to 4 and Comparative Examples 1 and 2 were prepared by uniformly mixing all the components according to the formulations in Table 1.

[0020]

[Table 1]

[0021] In Table 1, "Tomide 410" is
Polyamide resin epoxy adduct; active hydrogen equivalent 475 [
Fuji Kasei Kogyo Co., Ltd. product name]: "Versamide 280" is a polyamide resin epoxy adduct; active hydrogen equivalent: 250 [Henkel Hakusui Co., Ltd. product name]
: "Sanmide 315" is a polyamide resin epoxy adduct; Active hydrogen equivalent: 125 [Sanwa Chemical Industry Co., Ltd. product name]: "Sunmide 335" is a polyamide resin epoxy adduct; Active hydrogen equivalent: 70 [Sanwa Chemical Industry Co., Ltd.] Co., Ltd. product name]: "Tomide 558" is a polyamide resin epoxy adduct; active hydrogen equivalent: 2000 [Fuji Kasei Kogyo Co., Ltd. product name]: "Desmodur BL-1260" is an aromatic blocked isocyanate compound [ Bayer's product name]: "Takenate B-842N" is an aliphatic blocked isocyanate compound [Takeda Pharmaceutical Co., Ltd.'s product name].

Examples 5 to 8 According to the formulation in Table 2, an epoxy adduct of polyamide resin, a pigment and a solvent were first mixed and dispersed using an attritor until the particle size became 15 μm or less. Subsequently, a blocked isocyanate compound was mixed uniformly to prepare each paint of Examples 5 to 8.

[0023]

[Table 2]

[0024] In Table 2, "Sunmide 300" is
Polyamide resin epoxy adduct; active hydrogen equivalent: 550 [
Sanwa Kagaku Kogyo Co., Ltd. product name]: "Tomide 213" is a polyamide resin epoxy adduct; active hydrogen equivalent: 550 [Fuji Kasei Kogyo Co., Ltd. product name]
: "Versamide 115" is a polyamide resin epoxy adduct; active hydrogen equivalent: 180 [Henkel Hakusui Co., Ltd. trade name]: "Desmodur BL-3175" is an aliphatic blocked isocyanate compound [Bayer AG trade name]: "
"Coronate 2515" is an aliphatic blocked isocyanate compound [trade name of Nippon Polyurethane Industries Co., Ltd.]: "
"Takenate B-800" is an aromatic blocked isocyanate compound [trade name of Takeda Pharmaceutical Co., Ltd.]; "Takenate B-815" N is an aliphatic blocked isocyanate compound [trade name of Takeda Pharmaceutical Co., Ltd.]; It is.

Comparative Examples 3 to 6 (Preparation of main ingredient and curing agent) Third
According to the formulation in the table, the resin, pigment, and solvent as the base ingredients were first mixed and dispersed using an attritor until the particle size was 15 μm or less to prepare the base ingredient for each sample. A curing agent was prepared by putting a resin and a solvent as curing agent components into a container separate from the main resin and homogenizing them.

[0026]

[Table 3]

[0027] In Table 3, "Epicote 828" is
Epoxy resin [Product name of Yuka Shell Epoxy Co., Ltd.]:
"Epicoat 1001-75X" is an epoxy resin [Yuka Shell Epoxy Co., Ltd. trade name]; "Tomide 215-70X" is a polyamide resin epoxy adduct; active hydrogen equivalent 250 [Fuji Kasei Kogyo Co., Ltd.]
Product name: "Versamide 140" is a polyamide resin epoxy adduct; active hydrogen equivalent: 115 [Henkel Hakusui Co., Ltd. product name]
: "Tomide 225" is a polyamide resin epoxy adduct; active hydrogen equivalent: 115 [product name of Fuji Kasei Kogyo Co., Ltd.].

Examples 1 to 8 and Comparative Example 1 obtained above
~6 samples, the coated plate was a mild steel plate (JIS G-314
1, 0.8 x 70 x 150 mm, degreased) and tin foil (for free film production), painted using an applicator to a dry film thickness of 80 to 100 μm,
Test pieces were prepared by drying under the drying conditions shown in Table 4. However, for the two-component paints of Comparative Examples 3 to 6, the main ingredient and curing agent were uniformly mixed immediately before coating, and then the coating was applied. The following tests were conducted for each test piece. The results are shown in Table 4.

[0029]

[Table 4]

[Test method] - Impact resistance: JIS K-5
400 (1979) 6.13.3B method was applied, a weight of 1 kg was used, and if there was no abnormality at 50 cm, ○ (passed).
, Those with cracks were rated as × (fail). - Elongation rate: Measured at 20°C using Strograph W [Toyo Seiki Co., Ltd.], and an elongation rate of 30% or more was considered to be a pass.・Chipping resistance: Gravelometer [Suga Test Instruments Co., Ltd.]
[manufactured by] was applied, and the test conditions were an air pressure of 4 kg/cm2, 7
50 g of crushed stone was sprayed perpendicularly onto the painted surface of the test piece, and the state of peeling of the paint film was observed. A peeled area of 0% was considered acceptable.・Bending resistance: JIS K-5400 (1979) 6.1
6 was applied, and the test conditions were a mandrel diameter of 2 mmφ. ○ (pass) if there are no cracks on the painted surface, × if cracks have occurred
(failed). As is clear from the results in Table 4, the coating films of each of the coatings of Examples using the heat-curable resin composition of the present invention have better impact resistance, elongation rate, and It can be easily understood that the bending resistance is clearly superior in all respects.

[0031]

Effects of the Invention The coating film of the heat-curable one-component urethane resin paint based on the heat-curable resin composition of the present invention not only has excellent adhesion to the substrate, but also has particularly good impact resistance, elongation and It has extremely excellent mechanical properties such as chipping resistance,
It can be suitably used as an undercoat and intermediate coating for a wide range of applications, including automobiles.

Claims (1)

[Claims] 1. A thermosetting resin composition comprising a combination of a polyamide resin having an active hydrogen equivalent of 80 to 600 or an epoxy adduct of the resin and a blocked isocyanate compound.