JPH06306311A - Cationic-electrodeposition coating composition for producing printed wiring board - Google Patents

Abstract

PURPOSE:To obtain the title composition which gives a homogeneous coating film free from copper dissolution and developable with a weakly alkaline aque ous solution by treating a blend of a specific photoreactive anionic resin and a cationic resin with an acid to neutralize the cationic resin and dispersing the resulting blend into water. CONSTITUTION:A resin composition comprising a photoreactive anionic resin A and a cationic resin B in a ratio of about 95/5 to 20/80 is treated with an acid to neutralize the resin B. The resulting composition is dispersed into water to obtain the title composition. The resin A is photodegradable or photocurable. An example of the photodegradable anionic resin is obtained by reacting a modified naphthoquinone diazide with an acrylic resin by a known method. An example of the photocurable anionic resin consists mainly of a mixture of an alkyd resin modified with an unsaturated fatty acid and having a high acid value and an ethylenic compound having one or more polymerizable unsaturated bonds per molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cationic electrodeposition coating composition prepared by dispersing a photocurable or photodegradable anionic resin in water with a cationic resin, and particularly to a cationic electrodeposition coating composition suitable for the production of printed wiring boards. The present invention relates to a coating composition.

[0002]

2. Description of the Related Art Conventionally, to make a printed wiring board,
After laminating a photosensitive film on a copper foil-clad laminate and exposing and developing it with a photographic negative, the unnecessary copper foil other than the circuit pattern is etched, and then the photosensitive film is removed. As a result, the printed circuit is formed on the laminated plate which is an insulator.

Since the photosensitive film used in the above method has a large film thickness of about 50 μm, it is difficult to form a fine circuit pattern. Therefore, in recent years, a photoreactive coating film obtained by electrodeposition coating can be used to form a thin and uniform coating film that can be developed and has excellent photoreactivity on the surface of a copper clad laminate. An electrodeposition type photoresist is used.

As the method, an anionic type electrodeposition coating composition is obtained in which an electrodeposition coating film is obtained at an anode and is developed with an alkaline aqueous solution, and a cationic type is obtained in which an electrodeposition coating film is obtained at a cathode and is developed with an acidic aqueous solution. The methods using the electrodeposition coating composition are roughly classified.

[0005]

However, in the case of an electrodeposition coating using an anion resin, the copper of the substrate is eluted into the electrodeposition film during electrodeposition and reacts with the acid groups in the resin, making it insoluble in the developer. Then there is a problem to say. On the other hand, the electrodeposition coating composition using a cationic resin has a problem that it is not suitable for the situation that the mainstream of the developing solution is an alkaline solution in the current production line.

[0006]

The present inventor has conducted extensive studies to obtain an electrodeposition coating composition that solves the above-mentioned problems, and as a result, in a mixed resin of a specific photoreactive anion resin and a cation resin. The composition obtained by neutralizing the cationic resin of with an acid and dispersing in water can be subjected to cationic electrodeposition coating,
Further, they have found that they are developed with an alkaline developer, and have completed the present invention.

Thus, according to the present invention, the cationic resin (B) in the resin composition comprising the photoreactive anion resin (A) and the cationic resin (B) is neutralized with an acid and dispersed in water. A cationic electrodeposition coating composition for producing a printed wiring board is provided.

The present invention will be described in detail below. The photoreactive anion resin (A) in the cationic electrodeposition coating composition of the present invention can be classified into two types, a photodegradable type and a photocurable type.

The photodegradable anion resin is an alkali-soluble resin obtained by a conventionally known method. For example, JP-A-60-207139 and JP-A-64-9.
A modified product of a naphthoquinonediazide compound as disclosed in Japanese Patent No. 0270 is reacted with an acrylic resin by a known method, or a naphthoquinonediazide compound and an anion resin are simply mixed.

The photocurable anion resin is an alkali-soluble resin obtained by a conventionally known method,
For example, those described in JP-A-62-262856 can be used. The following can be mentioned as specific examples.

(1) A polymerizable compound obtained by adding a reaction product of a compound having a polymerizable unsaturated bond and a hydroxyl group in one molecule and a diisocyanate compound to a high acid value acrylic resin having a hydroxyl group in the skeleton. A component containing a saturated resin or a combination thereof with an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in one molecule as a main component:

(2) Polymerizability obtained by adding α / β ethylenically unsaturated dibasic acid or its anhydride to the unsaturated bond of the fatty acid chain in the esterified product of an epoxy resin having an epoxy group and unsaturated fatty acid A component containing a mixture of an unsaturated resin and an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in one molecule as a main component:

(3) A mixture containing a polymerizable unsaturated resin consisting of an unsaturated fatty acid-modified high acid value alkyd resin and an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in one molecule as a main component component:

(4) Component whose main component is a mixture of a polymerizable unsaturated resin comprising maleated oil and an ethylenically unsaturated compound having at least one polymerizable unsaturated bond in one molecule:

(5) A polymerizable unsaturated resin obtained by adding a compound having a polymerizable unsaturated bond and a glycidyl group in the molecule to a high acid value acrylic resin, or a polymerizable unsaturated bond in one molecule with these. Ingredients containing as a main component a combination of one or more ethylenically unsaturated compounds:

Next, the cationic resin (B) in the electrodeposition coating composition of the present invention is a water-dispersible resin obtained by a conventionally known method, for example, diglycidyl polyphenol such as bisphenol A or bisphenol F. An epoxy resin such as ether to which a primary or secondary amine is added, or an amino group-containing unsaturated monomer (for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N , N-dimethylaminopropyl (meth) acrylate and other unsaturated monomers (eg methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate styrene, (meth) acrylonitrile, etc.) The resin thus obtained can be mentioned.

The above-mentioned cationic resin (B) has an amino group content of 0.2 to 5 mol, preferably 0.
It is advantageous that the number average molecular weight is 3 to 2.0 mol and the number average molecular weight is 300 or more, preferably 1,000 to 30,000.

The compounding ratio of the photoreactive anion resin (A) and the cation resin (B) thus obtained is 9 by weight.
Range of 5/5 to 20/80, preferably 95/5 to 4
The range is 0/60. When the cationic resin (B) is 5% or less, water dispersibility and storage stability are deteriorated, which is not preferable. Further, when the cationic resin (B) is 80% or more, the solubility in the developing solution is low and differentiation by development cannot be performed.

In the present invention, examples of the acid used for neutralizing the cationic resin (B) include monocarboxylic acids such as formic acid, acetic acid, lactic acid, hydroxyacetic acid and butyric acid, which may be used alone or in a mixture. Can be used as The acid amount of the neutralizing agent is in the range of 0.3 to 2.0 equivalents relative to 1 mol of the amino group contained in the cation resin (B) skeleton. At this time, if it is less than 0.3 equivalent, the water dispersibility and the storage stability are deteriorated, which is not preferable. Also,
If it is 2.0 equivalents or more, the electrodeposition efficiency is generally lowered and it becomes difficult to obtain a desired film thickness.

In order to further improve the fluidity of the resin component dispersed in water, a hydrophilic solvent such as isopropyl alcohol, n-butanol, t-butanol, ethylene glycol mono (di) alkyl ether, diethylene glycol mono (di) alkyl. Ether, dioxane, tetrahydrofuran and the like can be added. The amount of the hydrophilic solvent used is preferably 300 parts by weight or less with respect to 100 parts by weight of the vehicle component.

In order to increase the coating amount on the object to be coated, hydrophobic solvents such as petroleum solvents such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate and butyl acetate; Alcohols such as 2-ethylhexyl alcohol; and the like can also be added. The amount of the hydrophobic solvent used is preferably 200 parts by weight or less based on 100 parts by weight of the resin component.

The photocurable anion resin (A) may contain a photopolymerization initiator, and as the photopolymerization initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzyl, diphenyl disulfide, tetramethyl thiuram. Monosulfide, eosin, thionine, diacetyl, Michler's ketone, anthraquinone,
Chloranthraquinone, methylanthraquinone, α-hydroxyisobutylphenone, p-isopropyl αhydroxyisobutylphenone, α · α ′ dichloro-4-phenoxyacetophenone, 1-hydroxy 1-cyclohexylacetophenone, 2 · 2 dimethoxy 2-phenylacetophenone, methylbenzoyl Formate, 2-
Methyl-1- [4- (methylthio) phenyl] -2.morphonino-propene, thioxanthone, benzophenone and the like can be applied, and the amount of these is 0.1 to 10 parts by weight with respect to 100 parts by weight of the resin component (solid content). If the amount is less than 0.1 parts by weight, the curability is lowered, and if it is more than 10 parts by weight, the mechanical strength of the cured film deteriorates. Further, dyes and pigments can be added as necessary.

The electrodeposition coating using the electrodeposition coating composition of the present invention is generally performed as follows. Cation electrodeposition coating bath pH 4.0-7.0, bath concentration (solid content concentration) 3 ~
25% by weight, preferably 5-20% by weight, bath temperature 15-
Controlled at 30 ° C., then immersed in an electrodeposited coating bath controlled in this way as a cathode on an insulating substrate coated with copper foil, and applied direct current of a constant voltage (1 to 400 V), or 1 to 40
It is performed by applying a direct current having a constant current of 0 mA / dm ² . Further, a predetermined voltage or current may be applied after the start of energization, or it may take 1 to 30 seconds to gradually increase to the predetermined current or voltage. In this case, energization time is 30
Seconds to 5 minutes are suitable. After electrodeposition coating, the object to be coated is lifted from the electrodeposition bath and washed with water, and then dried as it is, or if necessary, by air blow, hot air, etc.

Then, a pattern mask is formed on the unexposed electrodeposition coating film formed on the substrate and exposed with an actinic ray,
The portions other than the portions to be the conductor circuits are removed by the developing process.

In the present invention, the actinic ray used for exposure depends on the absorption amount of the photoreactive photosensitive group and / or the photopolymerization initiator, but an actinic ray having a wavelength of 300 to 700 nm is generally preferable. As these light sources, sunlight, mercury lamp,
There are xenon lamps and arc lamps. Curing of the coating film by irradiation with actinic rays is carried out within a few minutes, usually in the range of 1 second to 20 minutes.

The developing treatment is carried out by spraying a weak alkaline water on the surface of the coating film, and in the case of the photodegradable resin, the exposed portion is washed away, and in the case of the photocurable resin, the unexposed portion is washed away. Weak alkaline water is usually caustic soda,
It is possible to use those capable of imparting water solubility by neutralizing with free acid groups contained in the coating film, such as sodium carbonate, caustic potash, and ammonia water. For example, in the case of caustic soda water,
About 0.1% to 5% is suitable. If it is less than 0.1%, it is difficult to develop, and if it is more than 5%, the image portion may be damaged, which is not preferable.

Then, the copper foil portion (non-circuit portion) exposed on the substrate by the developing treatment is dissolved and removed by a usual etching treatment using ferric chloride or the like. After that,
The coating film on the circuit pattern is also dissolved and removed by a strong alkali such as caustic soda to form a printed circuit on the substrate.

[0028]

According to the present invention, the cationic electrodeposition method does not elute copper and a uniform coating film can be obtained, and development can be performed without residue using weak alkaline water. In addition, since the formed circuit surface does not elute copper, discoloration does not occur.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, parts by weight are simply referred to as parts.

Production Example 1 (Production of cationic resin 1) Methyl methacrylate 50 parts, ethyl acrylate 30
Solution, 10 parts of butyl acrylate, 10 parts of glycidyl methacrylate and 5 parts of azobisdimethylvaleronitrile were added dropwise to 90 parts of cellosolve kept at 80 ° C. in a nitrogen gas atmosphere over 3 hours. After the dropping, the mixture was aged for 1 hour, a mixed solution containing 1 part of azobisdimethylvaleronitrile and 10 parts of cellosolve was added dropwise over 1 hour, and further aged for 1 hour to obtain a glycidyl group-containing acrylic resin solution. Next, 4 parts of methylaminoethanol was added to this solution and reacted at 70 ° C. for 2 hours to obtain a saturated cation resin 1 (nonvolatile content concentration 51%, number average molecular weight 1
A solution of 5,000, amine number 35 mg KOH / g resin) was obtained.

Production Example 2 (Production of cationic resin 2) 55 parts of methyl methacrylate, 20 parts of ethyl acrylate
Part, 20 parts of 2-hydroxyethyl methacrylate, 5 parts of dimethylaminoethyl methacrylate and 2 parts of azobisisobutyronitrile were added to 90 parts of propylene glycol monomethyl ether held at 110 ° C. under a nitrogen gas atmosphere for 3 hours. It dripped in need. After the dropping, the mixture was aged for 1 hour, and a mixed solution containing 1 part of azobisdimethylvaleronitrile and 10 parts of propylene glycol monomethyl ether was added dropwise over 1 hour.
Saturated cationic resin 2 (nonvolatile content concentration 50
%, Number average molecular weight 20,000, amine value 18 mg KOH /
A resin g) solution was obtained.

Production Example 3 (Production of Photodegradable Anion Resin 3) 269 parts of 1,2-naphthoquinonediazide-5-sulfonic acid chloride and 1,345 parts of dioxane were added, and N-methylethanolamine 150 was stirred at room temperature. Part 1
Dropped over time. After completion of the dropping, stirring was continued for 3 hours, and I
The reaction was terminated after confirming that the absorption of amino groups near the R spectrum of 3,300 cm ^-1 disappeared. Next, isobutyl acetate was added to this solution and washed with deionized water.
Then, the solvent was distilled off, and the solid was obtained by drying under reduced pressure. 311 parts of the obtained solid matter and 233 parts of isophorone diisocyanate were put and reacted at 50 ° C. for 5 hours to obtain an isocyanate group-containing compound. Styrene 10 parts, methyl methacrylate 20 parts, ethyl methacrylate 41 parts, acrylic acid 10 parts, acrylic acid (2-hydroxyethyl)
A mixed solution of 19 parts and 6 parts of azobisisobutyronitrile was added dropwise to 56 parts of diethylene glycol dimethyl ether kept at 110 ° C. in a nitrogen gas atmosphere over 3 hours. After the dropping, the mixture was maintained for 1 hour, and then a mixture of 5 parts of diethylene glycol dimethyl ether and 0.5 part of azobisbutyrovaleronitrile was added dropwise over 1 hour, and the mixture was further maintained for 1 hour. Thereafter, the temperature was lowered to 50 ° C., 27 parts of the isocyanate group-containing compounds, were added 0.5 parts of dibutyltin diacetate, and retained for 5 hours, the absorption of isocyanate group in the vicinity 2,250Cm ^-1 in the infrared absorption spectrum It was confirmed that the solution was gone, and a photodegradation type anion resin 3 solution was obtained. The acid value was 61, the heating residue was 65%, and the weight average molecular weight was 18,000.

Production Example 4 (Production of photocurable anion resin 4) 35 parts of methyl methacrylate, 45 butyl acrylate
Part, 20 parts of acrylic acid and 2 parts of azobisisobutyronitrile were mixed in a nitrogen gas atmosphere at a temperature of 11 parts.
It was added dropwise to 90 parts of propylene glycol monomethyl ether kept at 0 ° C. over 3 hours. After the dropping, the mixture was aged for 1 hour, a mixed solution containing 1 part of azobisdimethylvaleronitrile and 10 parts of propylene glycol monomethyl ether was added dropwise over 1 hour, and the mixture was aged for 5 hours to obtain a high acid value acrylic resin (acid value 155 mgKOH / Resin g) solution was obtained. Then add glycidyl methacrylate 2 to this solution.
4 parts, hydroquinone 0.12 parts, and tetraethylammonium bromide 0.6 parts were added and reacted at 110 ° C. for 5 hours while blowing air to obtain a photocurable anion resin 4 (acid value about 50, unsaturated equivalent about 740, A solution having a number average molecular weight of about 20,000 was obtained.

Example 1 The cationic resin 1 obtained in Production Example 1 and the photodegradable anion resin 3 obtained in Production Example 3 were mixed at a solid content weight ratio of 40:60.
And neutralized with formic acid equimolar to the amino groups in the resin, and then water is added so that the solid content is 15% by weight, and the electrodeposition coating bath (pH 6.0) is added. Prepared.

Examples 2 to 4 An electrodeposition coating bath was prepared in the same manner as in Example 1 with the formulations shown in Table 1.

Comparative Example 1 The photoreactive anionic resin obtained in Production Example 4 was neutralized with triethylamine (1/2 mol based on the acid groups in the resin), and then the solid content was adjusted to 15% by weight. Water was added to prepare an electrodeposition coating bath (pH 7.0). Comparative Examples 2 to 4 An electrodeposition coating bath was prepared in the same manner as in Example 1 with the formulations shown in Table 1.

Storage stability The state of sedimentation of the paint after water dispersion and standing at 25 ° C. for 1 day and 1 week was examined. ◯: Stable with no sediment. Δ: Slight sedimentation is observed. X: Significant sediment is found under the container.

State of Electrodeposited Surface Using the electrodeposition coating baths obtained in Examples and Comparative Examples, a copper clad laminate was electrodeposited under the following conditions. Bath temperature 25 ° C Voltage 60mA / dm ² DC current Distance between electrodes 10cm Polar ratio Electrode / Coated plate = 1/2 Electrodeposition film thickness 20μm After electrodeposition coating, dry at 80 ° C for 10 minutes to obtain a smooth electrodeposition coating film. Obtained. ◯: There is no elution of copper and the film is transparent. X: Elution of copper is intense and the film is green.

Developability Next, the pattern film was brought into close contact with this coated plate with a vacuum device at room temperature of 25 ° C., and both sides were irradiated with 300 mJ / cm ² ultraviolet rays using a 3 kw ultra-high pressure mercury lamp. Formed pattern line after spraying 1% sodium carbonate solution at 25 ° C for 2 minutes. ◯: A good pattern line with no development residue. X: There is a development residue.

[0040]

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Takezoe 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa Kansai Paint Co., Ltd.

Claims (4)

[Claims] 1. A cationic resin (B) in a resin composition comprising a photoreactive anionic resin (A) and a cationic resin (B) is neutralized with an acid and dispersed in water. A cationic electrodeposition coating composition for producing a printed wiring board. 2. The cationic electrodeposition coating composition according to claim 1, wherein the photoreactive anionic resin (A) is a photodegradable resin. 3. The cationic electrodeposition coating composition according to claim 1, wherein the photoreactive anionic resin (A) is a photocurable resin. 4. The cationic electrodeposition coating composition according to claim 1, wherein the compounding ratio of the anion resin (A) / cationic resin (B) is 95/5 to 20/80 by weight.