JPS6330578A - Epoxy-resin-base resist ink composition - Google Patents

Abstract

PURPOSE:To obtain the title composition which has excellent flexibility, adhesiveness, heat resistance and electrical properties and moderate cure rate, and can be used in screen printing, by mixing an epoxy resin, an imidazole compound, and a long-chain dibasic acid anhydride. CONSTITUTION:100 pts.wt. epoxy resin (A) is mixed with 1-15pts.wt. imidazole compound (B) selected from among 2-ethyl-4-methylimidazole, 1-cyanoethyl-2- ethyl-4-methylimidazole, 2,4-diamino-6-[2-methylimidazolyl-(1)]-ethyl-s-triazine, and a 2,4-diamino-6-[ 2-ethyl-4-methylimidazolyl-(1) ]-ethyl-s-triazine/isocyanuric acid adduct, and a long-chain dibasic acid anhydride (C) comprising a 12-22C intermolecular polyacid polyanhydride of any one of formulas I-IV (wherein n is 3-10) in an amount of 0.05-0.9 equivalent based on one epoxy equivalent of component A. This mixture is kneaded so as to provide a particle size of <=10mum.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an epoxy resin-based resist ink composition for manufacturing flexible printed wiring boards that has excellent flexibility, adhesion, heat resistance, etc., and is particularly applicable to circuits. This invention relates to an epoxy resin resist ink composition suitable for protection and insulation.

Conventional Techniques Flexible printed wiring boards are manufactured by removing unnecessary copper foil other than the circuit from a flexible copper clad board by etching, or by printing or drawing a circuit on a base film using conductive ink. . The circuit formed in this way is protected from the outside world by mainly having a coverlay film bonded thereon by thermocompression, and finally into a sandwich structure.

Problems to be Solved by the Invention However, in conventional flexible printed wiring boards, coverlay films are expensive, and printed resistors on circuits tend to change characteristics during thermocompression bonding. was. Therefore, it is desired that a cheap, flexible, and fast-curing resist ink be developed in place of the coverlay film. Attempts have been made to mix flexible epoxy resins derived from polyethylene glycol, rubber components, polyesters, etc., but in each case, the moisture resistance and various physical properties of the cured product deteriorate significantly, and no satisfactory resist ink has been found. It has not appeared so far.

The general method for applying epoxy resin resist inks is screen printing, and in this case it is difficult to use curing agents that have a short pot life, such as amines or polyamides. Currently, some printing methods using ultraviolet curable inks are in practical use, but they are not always satisfactory in terms of flexibility and moisture resistance. Special Public Service 1977-
49588 discloses a solder resist ink for printed wiring boards that uses an epoxy resin and an imidazole compound as a curing agent and has excellent thermosetting properties, heat resistance, moisture resistance, chemical resistance, etc. Japanese Patent Publication No. 56-1
No. 57471 describes a Menki resist ink made of the same epoxy resin composition as mentioned above.

However, as electronic devices have become smaller and lighter in recent years, the use of flexible printed A-plates has become necessary in order to tightly pack components within a limited space. Although various attempts have been made to form flexible coatings without sacrificing the excellent characteristics of the compositions, there remain unresolved problems.

For example, a method in which a part of the epoxy resin is replaced with polyalkylene glycol diglycidyl ether or glycidyl ester of dimer acid has the drawbacks that the curing speed is slow and the moisture resistance of the cured coating film is insufficient. The method of replacing the resin with an epoxy resin or a butadiene rubber-modified epoxy resin had problems in workability, such as the very high viscosity of the composition and the inability to perform screen printing. When an acid anhydride such as methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride or dodecylsuccinic anhydride is used as a curing agent, a coating film with excellent visibility and moisture resistance can be obtained, but it is difficult to cure. Because high temperatures and long periods of time are required, the anhydride itself may deteriorate due to moisture in the working environment and solidify on the screen plate, or produce carboxylic acid, which prevents the designed properties from being exhibited. In addition, in this case, there was a risk that environmental pollution would occur due to the release of anhydride.

Means for Solving the Problems In view of the above circumstances, the inventors of the present invention have made extensive studies and have developed an epoxy resin composition suitable for resist inks that has good flexibility, adhesion, and heat resistance. I ended up discovering something.

In other words, by blending an imidazole compound and a long-chain dibasic acid anhydride (intermolecular polyacid polyanhydride with 12 to 22 carbon atoms) as essential components as a curing agent to the epoxy resin, a high degree of flexibility and rubber elasticity can be achieved. We have discovered a useful epoxy resin resist ink composition that has both appropriate curing speed and screen printability.

Epoxy resins suitable for the practice of the invention include polyglycidyl ethers of polyhydric phenols that are liquid at room temperature, such as diglycidyl ether of bisphenol A, bisphenol F
Other examples include epoxidized phenol nopola resin, epoxidized talesol novolak resin, or solid epoxy resin dissolved in a solvent.

Imidazole compounds suitable for carrying out the present invention include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 2-heptadecylimidazole (hereinafter referred to as C, ffZ
), 2-phenyl-4-methylimidazole and 1-position cyanoethylated products of these 2-substituted imidazole compounds, such as l-cyanoethyl-2-ethyl-4-
Methylimidazole (hereinafter abbreviated as 2E4MZ CN)
, carboxylates of these imidazole compounds, 2.4
-diamino-6-(2-methylimidazolyl-(1))
-ethyl-3-triazine (hereinafter abbreviated as 2MA),
2.4-diamino-6-(2-ethyl-4-methylimidazolyl-(1))'-ethyl-s-triazine, 2,
4-diamino-6-(2-undecylimidazolyl-(
1)) -ethyl-s-triazine, 2,4-diamino-6-(2-methylimidazolyl-(1))-ethyl-
3-triazine isocyanuric acid adduct (hereinafter referred to as 2MA-
OK), 2-phenyl-4゜5-dihydroxymethylimidazole (hereinafter abbreviated as 2PH2), 2-phenyl-4-methyl-5-hydroxymethylimidazole (
(hereinafter abbreviated as 2P4MH2). Particularly latent imidazole compounds, such as C1t Z -2M Z
, 2MA-OK, 2PH2, 2P4MH2, etc., it is also possible to obtain a -liquid epoxy resin resist ink composition.

Furthermore, by using an imidazole compound that is highly reactive with epoxy resins, it is also possible to obtain a composition that has good low-temperature curability. In the case of a two-component epoxy resin resist ink composition, the imidazole compound is usually dissolved or dispersed in a long-chain dibasic acid anhydride, but in the case of using an imidazole compound with relatively high latency, the epoxy resin side is used. (Also, it may be dispersed to the curing agent side.)

The amount of imidazole compound added in carrying out the present invention is
The amount is 1 to 15 parts by weight, preferably 3 to 10 parts by weight, based on 100 parts by weight of the epoxy resin.

If the amount of the imidazole compound added exceeds this range, a cured coating film with poor moisture resistance will be obtained, and the pot life will also be extremely short. It is extremely time consuming and impractical.In addition, two or more types of imidazole compounds may be used in combination to obtain appropriate reactivity.

In addition, dicyandiamide or the like may be used in combination to further improve adhesiveness.

The long-chain dibasic acid anhydride as a curing agent suitable for carrying out the present invention is a dibasic acid obtained by ring-opening trimerization of cyclohexanone with Fenton's reagent, or a dibasic acid obtained by ring-opening trimerization of cyclohexanone, or a dibasic acid obtained by ring-opening trimerization of cyclohexanone, or a dibasic acid obtained by ring-opening trimerization of cyclohexanone, or a dibasic acid obtained by performing this reaction in the presence of an olefin to form olefin molecules between 1 to 2 molecules. It is an intermolecular polyacid polyanhydride obtained by intermolecular dehydration condensation of a sandwiched dibasic acid or a further hydrogenated dibasic acid, and representative examples thereof are shown by ■ to ■ in the formula below. In particular, the intermolecular polyacid polyanhydride represented by formula (1) is suitable for use because it is liquid at room temperature.

The amount of long chain dibasic acid anhydride added in the practice of the present invention is
O,OS~0.0 for 1 equivalent of epoxy resin. g equivalent, preferably 0.1 to 0.7 equivalent.

As the amount of long-chain dibasic acid anhydride added increases, flexibility increases and a soft cured coating film is obtained, but if it exceeds the above range, curing failure on the coating film surface is likely to occur, In this case, the cured coating becomes too hard and cannot achieve the intended purpose.

In the composition of the present invention, pigments, fillers,
Solvents, plasticizers, reactive diluents, leveling agents, and other additives can be added.

Examples and Comparative Examples Epoxy resins, imidazole compounds, long-chain dibasic acid anhydrides, and other additives were blended in the ratios shown in Tables 1 and 2, and the particle size was determined using a three-roll mill. 10
A resist ink composition was manufactured by uniformly dispersing and kneading the resist ink composition to a size of microns or less.

Storage stability and performance tests were conducted on the compositions obtained by the formulations of each Example and Comparative Example, and the results were as shown in Table 3.

The numerical units in Tables 1 and 2 are parts by weight.

Note: (1) is from Yuka Shell Epoxy, (2) is from Dow Chemical, (3) and (4) are from Shikoku Chemical Industry, (5) and (6) are from Intermediate Oil Manufacturing, and (7) is from Japan. Aerosil Kogyo ■ and (8) are products of Shin-Etsu Chemical ■, and (5) IPU-
22AH is a long-chain dibasic acid anhydride represented by the formula (■), (
5L-20AH in 6) is a long chain dibasic acid anhydride represented by the above formula (1).

Note) In the table, +ll or 8) is the same as Table ~1,
In (9), a product manufactured by Shikoku Kasei Kogyo was used.

Table 3 Storage stability and performance test of cured product However, a coating film with a thickness of 20 microns was formed on a PET film by screen printing, and this was cured by heating at 120'C for 130 minutes.

Note) Cross-cut peeling test was conducted according to α[11 JIS-D-0202.

Pencil hardness was measured according to αυ JIS-5400.

The substrate film on which the coating film was formed according to αδ JIS-5400 was folded 50 times using a bending tester, and it was visually confirmed whether there were any cracks in the coating film.

α After immersing in a molten solder bath at 1260°C for 30 seconds, the appearance of the coating film was observed for blistering and peeling, and JIS-D-02
A cross-cut peeling test was conducted according to 02.

α荀 The number of days until the viscosity reached twice the initial viscosity was measured.

Effects of the Invention The epoxy resin resist ink composition of the present invention has excellent mechanical and electrical properties, has an appropriate curing speed, and can be screen printed, so it is suitable for printed wiring boards, especially flexible printing. As a protection and insulation coating for wiring boards, a major procedural amendment (voluntary) was published in August 1986 (.

Claims (5)

[Claims] (1) An epoxy resin-based resist ink composition containing an epoxy resin, an imidazole compound, and a long-chain dibasic acid anhydride (intermolecular polyacid polyanhydride having 12 to 22 carbon atoms) as essential components. (2) As an imidazole compound, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4
-methylimidazole, 2,4-diamino-6-{2-
A group consisting of methylimidazolyl-(1)}-ethyl-s-triazine or 2,4-diamino-6-{2-ethyl-4-methylimidazole-(1)}-ethyl-s-triazine/isocyanuric acid adduct The epoxy resin resist ink composition according to claim (1), which uses an ink selected from the following. (3) As the long chain dibasic acid anhydride, the following formulas (1) to (
The epoxy resin resist ink composition according to claim (1), which uses one or more of the compounds represented by (6). Formula (1) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Formula (2) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Formula (3) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Formula (4) ▲ Mathematical formulas, chemical formulas , tables, etc. ▼ Formula (5) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Formula (6) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [However, any of the above formulas (1) to (6) Each n represents a numerical value in the range of 3 to 10. ] (4) The epoxy resin resist ink composition according to claim (1), wherein the imidazo compound is contained in a proportion of 1 to 15 parts by weight based on 100 parts by weight of the epoxy resin. (5) The epoxy resin-based resist ink composition according to claim (1), wherein the long-chain dibasic acid anhydride is contained in a ratio of 0.05 to 0.9 equivalents per 1 epoxy equivalent of the epoxy resin.