JPS6354027B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel and useful coating composition, and more particularly to a curable, solvent-resistant, low-temperature curing coating composition comprising a specific polyfunctional epoxy resin and an amino group-containing compound as essential vehicle components. The present invention relates to a curable composition for coating that provides a coating with excellent properties, corrosion resistance, adhesiveness, heat resistance, electrical properties, and secondary physical properties. In general, epoxy resins have excellent corrosion resistance, adhesiveness, heat resistance, electrical properties, curing properties, and other properties due to their unique structure, and for this reason, they can be used in combination with various curing agents to create coating materials.
Not only does it have a wide range of uses in adhesives, electrical parts, civil engineering and buildings, but it can also be used as a modifying agent for various resins, making it extremely important industrially. The reality is that resins are required to have even higher performance in each field of use. For example, in the field of coating materials, from liquid low molecular weight bisphenol A type epoxy resins to solid high molecular weight bisphenol A type epoxy resins, amine curing agents, acid anhydride curing agents, acid anhydride curing agents, etc. Can paints, pre-coated metal paints, tar epoxy resin paints, pure epoxy paints, etc. by curing at room temperature or by heating in combination with curing agents, phenolic resins, melamine resins, acrylic resin curing agents, latent curing agents, and other curing agents. It's being used. However, not only are long-term corrosion protection and heat resistance insufficient, but also resistance to organic and inorganic acids and alkalis, as well as various solvents, is particularly inadequate for cold-curing coating materials. , because the above-mentioned performances are insufficient,
The current situation is that there is a strong demand for measures to improve these various performances. In addition, in the so-called electrical field such as electrical insulation, bisphenol A type epoxy resins are used in combination with various curing agents for casting, lamination, embedding, sealing, and other uses, as described above. In addition to the use of brominated epoxy resins that have flame retardancy, it is also possible to use epichlorohydrin and a novolac resin obtained from the phenol and/or substituted phenols and a formaldehyde supply substance to improve heat resistance. Although so-called novolac-type epoxy resins obtained from polyamide-based curing agents are widely used, their applications are severely limited because they are not compatible with polyamide-based curing agents, and they are not compatible with compatible curing agents. Although the combination of the above certainly increases the cured density and the degree of heat resistance, on the other hand, the cured resin generally becomes brittle and "cracks" during post-processing or repeated heating and cooling.
The current situation is that the field of use is limited due to the occurrence of cracks and cracks, and moreover, there is a high incidence of defective products. However, as a result of extensive research over many years in view of the current situation as described above, the present inventors have developed a new technology that maintains the advantages of the bisphenol A type epoxy resin, which is the most commonly used at present, while maintaining its heat resistance properties. , a new product that has improved low-temperature curing properties and chemical resistance, and also has the heat resistance of novolak type epoxy resins, while being more flexible and having significantly improved compatibility with various curing agents. The present inventors have discovered a polyfunctional novolac type epoxy resin that is useful for various purposes, and have completed the present invention. That is, the present invention provides an epoxy resin (A) obtained from polyhydric phenols and epichlorohydrin.
A phenolic resin obtained from phenol and/or substituted phenols and a formaldehyde supply substance and epichlorohydrin are added to the precondensate obtained through a step of precondensing excess polyhydric phenols (that is, a precondensation step). A polyfunctional epoxy resin () obtained through a step of co-condensing a novolak type epoxy resin (B), which is a reaction product with a polyfunctional epoxy resin (B), and an amino group-containing compound () as essential vehicle components. The object of the present invention is to provide a coating composition comprising the above-described excellent coating properties. Here, together with the polyhydric phenols used to obtain the epoxy resin (A) or the polyhydric phenols used as the condensation component for the precondensation, 2,2'-bis(p-hydroxy Bis(p-hydroxyphenyl)alkanes such as phenyl)propane (commonly known as "bisphenol A") or bis(p-hydroxyphenyl)methane (commonly known as "bisphenol F") and their nuclear halogen substituted products Refers to all polyhydric phenols including dihydroxybenzenes such as 1,3-dihydroxybenzene (commonly known as "resol") and their alkylated products or nuclear halogen-substituted products; and also diphenols such as bisphenolsulfone. Of these, the above-mentioned bisphenol A or bisphenol F is the most common.
It may be even more useful to use monophenols such as phenol, cresol, or octylphenol; and dinuclear or higher phenolic resins obtained from these monophenols and a formaldehyde supplying substance as described below. Therefore, the term "polyhydric phenols" as used in the present invention should be understood in this sense. The method for obtaining the above-mentioned epoxy resin (A) from such polyhydric phenols and epichlorohydrin is described, for example, in "Production and Application of Epoxy Resins" edited by Kobunshi Kagaku Kankai (published on November 10, 1960). Just follow the method given. In carrying out the precondensation step, which is the first step of the method of the present invention, the term "precondensed" means that the epoxy equivalent of the precondensate obtained through such step is at least 3000 g/equivalent (hereinafter referred to as
It is abbreviated as 3000g/eq. ), and in this precondensation step, it is necessary to carry out condensation in the presence of a stoichiometrically excessive amount of polyhydric phenols relative to the epoxy resin (A). In other words, it is necessary for one or more phenolic hydroxyl groups present in the polyhydric phenols to exist for each epoxy group present in the epoxy resin (A), and more preferably for each epoxy group present in the epoxy resin (A). A suitable range is 1.2 to 4.0 hydroxyl groups per one hydroxyl group. Thus, in the first step, the precondensate can be obtained by simply heating the above-mentioned epoxy resin (A) and the above-mentioned polyhydric phenols, but by using an appropriate catalyst and at an appropriate temperature. The latter method is recommended because a precondensate can be easily obtained depending on the selection. Typical catalysts that promote these reactions include inorganic alkaline hydroxides or halides such as lithium hydroxide or sodium hydroxide; trimethylamine, triethylamine, benzyldimethylamine, N-methylpiperazine or N-methylmorpholine. Tertiary amines or their hydrochlorides such as; quaternary ammonium salts such as tetramethylammonium chloride, tetramethylammonium bromide or phenyltrimethylammonium chloride; imidazole compounds such as imidazole or 2-ethylimidazole; ; acidic phosphorus compounds such as triphenylphosphone; inorganic alkali salts of organic carboxylic acids such as calcium acetate; and quaternary ammonium salt type ion exchange resins. By adding appropriate amounts of these, the reaction is effectively On the other hand, the reaction temperature is usually in the range of 50 to 260°C, preferably 100 to 200°C. At this time, the reaction can also be carried out by diluting it with a known and commonly used appropriate solvent, which is a useful means. On the other hand, the above-mentioned cocondensation step, which is the second step of the method of the present invention, is a step in which the precondensate obtained in the previous precondensation step is further reacted with a novolak type epoxy resin. Epoxy resin (B) refers to a resin obtained by further reacting epichlorohydrin with a phenolic resin obtained from phenol and/or substituted phenols and a formaldehyde supply substance, and is a typical substituted phenol. Examples include cresol or octylphenol, while typical formaldehyde-supplying substances include formalin or paraformaldehyde. In this way, the second step of co-condensing the novolac type epoxy resin (B) with the precondensate is also a reaction between the phenolic hydroxyl group and the epoxy group. This can be done in the same way as when obtaining . That is, the ratio of the epoxy resin (B) to the precondensate is such that the phenolic hydroxyl group of the precondensate is 0.01 to 0.5 chemical equivalent of epoxy group (that is, one epoxy group) of the resin (B). equivalent (i.e. 0.01-0.5 pieces), preferably 0.02-0.4
It is preferable to select within the range of chemical equivalent (that is, 0.02 to 0.4). Other reaction catalysts, reaction temperatures, etc. may be the same as in the first step. If the number of phenolic hydroxyl groups is less than 0.01, the compatibility with amine curing agents and the flexibility of the curing agent will not be sufficient, while if the number exceeds 0.5, the heat resistance of the cured product will only decrease. However, since gelation tends to occur during the reaction, both are unfavorable. The thus obtained polyfunctionally modified novolac type epoxy resin (B) contains aliphatic polyamines, alicyclic polyamines, aromatic polyamines, cyanoethylated polyamines, and glycidyl group-containing compounds, as in the case of conventional bisphenol A type epoxy resins. and various polyamines (hereinafter referred to as glycidyl polyamine adducts), polyamides, polyamide adducts (hereinafter referred to as polyamide adducts), acid hydrazide or dicyandiamide, etc. By curing it in combination with an agent, it can be preferably used for various applications such as coating, civil engineering, adhesives, and electrical applications.In particular, it has a high degree of durability against acids, alkalis, solvents, and gases, as well as water resistance. It is useful in the field of coatings or adhesives that require it, or in electrical fields where heat resistance, flexibility, electrical insulation, etc. are required. Here, aliphatic polyamine is a chain aliphatic polyamine such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylene diamine or diethylaminopropylamine; N-aminopiperazine, menthendiamine, isophorone diamine or 1,
It is a general term for cyclic aliphatic polyamines such as 3-bis(aminomethyl)cyclohexane; or aliphatic aromatic polyamines such as m- and/or p-xylene diamine, or a trimer of m-xylene diamine. Typical examples of the alicyclic polyamine include hydrogenated diaminodiphenylmethane and isophorone diamine, and typical examples of the aromatic polyamine include m-phenylenediamine, diaminodiphenylmethane, and diaminodiamine. Typical cyanoethylated polyamines include biscyanoethyl diethylenetriamine, bisaminoethyl triethylenetetramine, or bisaminotetraethylenepentamine, and the glycidyl polyamine adducts include diphenyl sulfone. Typical examples include those in which ethylene oxide, propylene oxide, styrene oxide, butyl glycidyl ether, phenyl glycidyl ether, or various epoxy resins are added as modifiers to the various polyamines mentioned above; Typical examples include those made by condensing excess amounts of the various polyamines mentioned above with fatty acids, but in general, fatty acid dimers (commonly known as "dimer acids") are used as fatty acids. It will be done. Typical polyamide adducts include those made by adding epoxy resin or other epoxy group-supplying substances to the various polyamides mentioned above, and typical acid hydrazides include amber. Acid hydrazide, adipic acid hydrazide, isophthalic acid hydrazide,
Examples include p-oxybenzoic acid hydrazide, salicylic acid hydrazide, and phenylaminopropionic acid hydrazide. The ratio of each essential component of the polyfunctional epoxy resin () and the amino group-containing compound () constituting the composition of the present invention cannot be uniquely determined depending on the purpose, required characteristics, etc. , usually 0.1 to 1.5 of each active hydrogen present in the compound (), preferably 0.5 to 1.0 per chemical equivalent of epoxy group in the resin (), that is, one epoxy group.
This is in proportion to the number of individuals. The composition of the present invention obtained in this way is sufficiently useful as a coating material by itself, but depending on the purpose of use, it may be added with known and commonly used colorants, aggregates, reinforcing materials, solvents,
Flexibility agents, plasticizers (softeners), flow modifiers (dispersing agents), cure accelerators, cure retarders, surfactants, thickeners, flame retardants, thixotropes, bituminous substances or fillers. Various additives such as additives may be added. The composition of the present invention can be applied to the surface of metal, wood, plastics, stone, slate, concrete, mortar, fibers, paper, ceramics, porcelain, glass, leather, film, rubber, or other substrates by brushing, spray coating, or coating. By applying by roll coating, blade coating, flow coating, electrostatic coating, or other methods, and then curing and drying by natural drying, heat treatment, or other treatment,
It provides a cured coating film with particularly excellent solvent resistance, corrosion resistance, adhesion, heat resistance, electrical properties, and secondary physical properties, so it is suitable for various plants, tanks, pipes, etc.
It is useful in a wide range of applications such as primers and maintenance coatings for ships, bridges, steel frames, vehicles and other large structures. Next, the present invention will be specifically explained with reference to Reference Examples, Examples, and Comparative Examples, where all parts and percentages are based on weight unless otherwise specified. Reference Example 1 [Example of preparation of polyfunctional epoxy resin ()] In a four-necked flask equipped with a stirrer, a nitrogen gas introduction device, and a thermometer, ``Epicron 850'' (Epichlorohydrin Bis. manufactured by Dainippon Ink & Chemicals Co., Ltd.) Phenol A type epoxy resin; epoxy equivalent =
190 parts of 190) (that is, equivalent to one epoxy group),
Add 228 parts of bisphenol A (that is, equivalent to 2 hydroxyl groups) and 0.2 part of a 1% aqueous solution of caustic soda, and heat at 180°C for 5 minutes while purging with nitrogen gas.
By reacting for a long time, the epoxy equivalent is
35,000 and a hydroxyl equivalent of 414 was obtained.
Hereinafter, this will be abbreviated as PC-1. Then this
60 parts (0.145 hydroxyl groups) of PC-1, 180 parts (epoxy group 1 piece), 0.24 parts of 1% aqueous tetramethylammonium chloride solution and xylol 80
After reacting at 140℃ for 4 hours, 80 parts of methyl isobutyl ketone was added and dissolved, resulting in an epoxy equivalent (solid content) of 285 and a non-volatile content.
A polyfunctional epoxy resin varnish of 59.7% was obtained. Hereinafter, this will be abbreviated as E-1. Reference Example 2 [Preparation example of polyfunctional epoxy resin ()] In the same manner as Reference Example 1, "Epicron 850" was prepared.
By using 190 parts of bisphenol A, 171 parts of bisphenol A (equivalent to 1.5 hydroxyl groups) and 0.2 parts of 10% tetramethylammonium chloride aqueous solution at 160°C for 4 hours and then at 190°C for 2 hours, the epoxy equivalent was 11,000. A precondensate having a hydroxyl equivalent of 722 was obtained. Hereinafter, this will be abbreviated as PC-2. Next, using 50 parts of this PC-2 (0.07 hydroxyl groups), changing the amount of 1% tetramethylammonium chloride aqueous solution to 0.23 parts, omitting the use of any solvent, and further changing the reaction conditions. 145
A polyfunctional epoxy resin having an epoxy equivalent of 255 was obtained in the same manner as in Reference Example 1, except that the temperature was kept at 6 hours. Hereinafter, this will be abbreviated as E-2. Reference Example 3 [Preparation example of polyfunctional epoxy resin ()] Except that the amount of PC-2 used was 100 parts (0.14 hydroxyl groups) and the amount of 1% tetramethylammonium chloride aqueous solution was changed to 0.28 parts. teeth,
The same operation as in Reference Example 2 was repeated to obtain a polyfunctional epoxy resin having an epoxy equivalent of 325. Hereinafter, this will be abbreviated as E-3. Reference Example 4 [Preparation example of polyfunctional epoxy resin ()] Except that the amount of PC-2 used was 180 parts (for 0.25 hydroxyl groups) and the amount of 1% tetramethylammonium chloride aqueous solution was changed to 0.36 parts. teeth,
A polyfunctional epoxy resin having an epoxy equivalent of 470 was obtained in the same manner as in Reference Example 2. Hereinafter, this will be abbreviated as E-4. Reference Example 5 [Preparation example of polyfunctional epoxy resin ()] The amount of bisphenol A used was 149 parts (hydroxyl group 1.3
A precondensate having an epoxy equivalent of 9,500, a hydroxyl equivalent of 1,257, and a melting point (ring and ball method) of 115° C. was obtained in the same manner as in Reference Example 2, except that the precondensate was changed to 115°C (ring and ball method). Hereinafter, this will be abbreviated as PC-3. Next, using 220 parts (0.18 hydroxyl groups) of this PC-3, 1
% tetramethylammonium chloride aqueous solution was changed to 0.40 parts, and the amounts of xylene and methyl isobutyl ketone were changed to 133 parts and 134 parts, respectively, to obtain the epoxy equivalent (solid content) in the same manner as in Reference Example 1. is 480, the viscosity (Gardner method at 25°C; the same applies hereinafter) is Z <sub>s</sub> ,
A polyfunctional epoxy resin varnish with a nonvolatile content of 60.1% was obtained. Hereinafter, this will be abbreviated as E-5. Reference Example 6 [Preparation example of polyfunctional epoxy resin ()] Except that 200 parts (for 2 hydroxyl groups) of bisphenol F was used instead of bisphenol A.
A precondensate having an epoxy equivalent of 27,000 and a hydroxyl equivalent of 390 was obtained in the same manner as in Reference Example 1. Hereinafter, this will be abbreviated as PC-4. Next, this PC-4
For 55 parts (0.14 hydroxyl groups), "Epicron N
-740'' in place of 220 parts (one epoxy group) of ``Epiclon N-673'' (Dainippon Ink Chemical Co., Ltd.)
A cresol novolac type epoxy resin manufactured by Manufacturer Co., Ltd.; epoxy equivalent = 220) was used, the amount of 1% tetramethylammonium chloride aqueous solution used was 0.28 parts, and the amounts of xylol and methyl isobutyl ketone were each 92 parts. , the epoxy equivalent (solid content) was 312 in the same manner as Reference Example 1,
A polyfunctional epoxy resin varnish with a viscosity of Y and a non-volatile content of 60.0% was obtained. Hereinafter, this will be abbreviated as E-6. Reference Example 7 [Preparation example of polyfunctional epoxy resin ()] 180 parts (one epoxy group) of "Epicron"
830'' (Epichlorohydrin Bisphenol F type epoxy resin manufactured by Dainippon Ink & Chemicals Co., Ltd.; epoxy equivalent = 180) and 150 parts (1.5 hydroxyl groups) of Bisphenol F. 2
Similarly, the epoxy equivalent is 8900 and the hydroxyl equivalent is
A precondensate named 660 was obtained. Below, this is PC-5
It is abbreviated as Next, 90 parts (0.14 hydroxyl groups) of this PC-5 were used, and 1% of the catalyst was also 0.3 parts.
The epoxy equivalent (solid content) was prepared in the same manner as in Reference Example 5, except that the aqueous solution of trimethylammonium chloride was used, xylol was changed to 103 parts, and methyl isobutyl ketone was changed to 104 parts.
350, a viscosity of _Z2 and a non-volatile content of 60.0% was obtained. Below, this is E-7
It is abbreviated as Reference Example 8 [Preparation example of polyamine adduct] Put 100 parts of triethylenetetramine into a four-necked flask equipped with a stirrer, nitrogen gas introduction device, dropping funnel, and thermometer, and heat to 80°C while purging with nitrogen gas. When the temperature reached the same temperature, "Epicote 1001" (epoxy resin manufactured by Siel in the Netherlands; epoxy equivalent = 475, 75% xylene solution) was added.
75 parts were added dropwise over 2 hours, the temperature was further raised to 100°C, and stirring was continued for 2 hours. Next, residual triethylenetetramine was removed by distillation under reduced pressure, and 53.8 parts of toluene and 53.8 parts of n-butanol were added to obtain a target solution having an amine value of 380 and an active hydrogen equivalent of 125. Examples 1 to 7 and Comparative Examples 1 and 2 The polyfunctional epoxy resins () and amino group-containing compounds () obtained in Reference Examples 1 to 7, respectively, were
The compositions of the present invention were prepared by using the blending ratios shown in Table 1 and stirring and mixing by a known and commonly used method. For comparison, as commercially available epoxy resins, "Epiclon 860" (epichlorohydrin bisphenol A type epoxy resin manufactured by Dainippon Ink and Chemicals Co., Ltd.; epoxy equivalent = 250) and "Epiclon 1050" (same as above; Epoxy equivalent =
A control coating composition was also prepared in the same manner except that 475) was used in place of the above-mentioned polyfunctional epoxy resin (2). For the various compositions obtained in this way, coating films were obtained in the following manner, and the solvent resistance, adhesion, low-temperature curability, and corrosion resistance of each coating film were evaluated, and the results are summarized in the same table. . (1) Painting material: Sandblasted steel plate specified in JIS G-3141 (2 x 75 x 100mm) (2) Painting method: JIS K-5400-1970 on the above material
3.5: By method (1), the thickness of the coating film after drying is
It was coated to a thickness of 300±2 μm. (3) Paint film drying method: Dry for 14 days in a constant temperature room at 25°C. The dried coating film thus obtained was used as a test piece and subjected to various tests. (4) Test method: Approx.
500 ml was poured into the solvent, and then the test piece was immersed therein so that 60% of the test piece was vertically immersed in the solvent. Moisture resistance test and salt water spray resistance test - Tests were carried out in a conventional manner using a commonly used humidity resistance tester and salt water spray resistance tester. (5) Judgment and evaluation: After pulling up the test piece and wiping it clean with absorbent cotton, the painted surface was visually observed and judged based on whether any abnormalities such as wrinkles, cracks, blisters, peeling, etc. were observed. ``Pass'' if no abnormalities were observed.
If any abnormality was found in any of the tests, it was judged as a "fail". Low temperature curing property is JIS K-
5400−1970 5, 10(2)(b) at 5℃
Judgment will be made after 36 hours.

[Table] * Both epoxy resin and curing agent are expressed as solid content values.

Claims (1)

[Scope of Claims] 1 () Excess polyhydric phenols are condensed in advance to the epoxy resin (A) obtained from polyhydric phenols and epichlorohydrin to obtain a precondensate, and then phenol is added to this precondensate. and/or a polyfunctional epoxy resin obtained by co-condensing a novolac type epoxy resin (B) which is a reaction product of a phenolic resin obtained from substituted phenols and a formaldehyde supplying substance and epichlorohydrin; A curable coating composition comprising a compound as a main vehicle component. 2. Claim 1, wherein the amino group-containing compound is an aliphatic polyamine.
The composition described in Section. 3. Claim 1, wherein the amino group-containing compound is an alicyclic polyamine.
The composition described in Section. 4. Claim 1, wherein the amino group-containing compound is an aromatic polyamine.
The composition described in Section. 5. The composition according to claim 1, wherein the amino group-containing compound is a cyanoethylated polyamine. 6. The composition according to claim 1, wherein the amino group-containing compound is an adduct of a glycidyl group-containing compound and polyamines. 7. The composition according to claim 1, wherein the amino group-containing compound is a polyamide. 8. The composition according to claim 1, wherein the amino group-containing compound is a polyamide adduct. 9. The composition according to claim 1, wherein the amino group-containing compound is an acid hydrazide. 10 Claim 1, wherein the amino group-containing compound is dicyandiamide.
The composition described in Section.