JP3150207B2 - Screen printing ink composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing ink composition for a strippable masking material used for wiring boards and the like.

[0002]

2. Description of the Related Art Conventionally, as a masking method in a plating process which has been used for a printed wiring board or the like, a solvent-based masking material in which an alkali-soluble synthetic resin is dissolved in an organic solvent as a binder component, Emulsified and processed on a wiring board using a water-based masking material, etc., and peeled off from the wiring board after plating with an alkaline aqueous solution, or into an arbitrary shape using a masking film subjected to adhesive processing etc. After the cut and paste plating process, there is a method of peeling off from the wiring board. However, in the former method, it is necessary to remove the solvent in the masking material and to use an alkaline aqueous solution at the time of peeling, and in the latter method, it is necessary to manufacture and paste an expensive mold, and in any case, There is a disadvantage that the work process becomes complicated. Recently, a non-solvent type masking material using a photocurable resin has been proposed for these methods (JP-A-59-51962, JP-A-1-141904, JP-A-1-141904).
The method of stripping is based on the removal of an alkaline aqueous solution, and does not eliminate the complexity of the process. Solvent-free and strippable coating materials have also been proposed (JP-A-3-139573). However, when used as a screen printing masking material for printed wiring boards,
Due to lack of screen printing suitability, there are drawbacks in that the obtained coating film surface becomes non-uniform and foaming increases. As a result, the plating solution contaminates places other than the necessity during the plating process, and the performance as a masking material is not recognized.

In order to solve such difficulties, the present inventors have conducted intensive studies on a radiation-curable masking material excellent in screen printing suitability. As a result, a resin composition containing a specific urethane (meth) acrylate resin has been found to be suitable for screen printing. Was found to be extremely excellent. (1991 Patent Application No. 260524) Thereafter, as a result of further intensive studies on such a masking material, it has been revealed that it is sometimes insufficient to simply impart printability. That is, before the material masked on the wiring board is processed in the plating layer, which is the original purpose, a pretreatment process for facilitating plating may be performed. In the final stage of this process, the following process is performed. The problem became clear. In the final stage of the pretreatment step, there is a step of washing and drying the masked wiring board in order to prevent the pretreatment liquid from being mixed into the plating treatment liquid. When the wiring boards are stacked and stored immediately after the drying, the masking film adheres to the back side of the wiring board, and when the wiring boards are separated from each other, a phenomenon occurs that the masking film sticks to the back side of the wiring board and peels off. There was a problem.

[0004]

There is a need for a masking material which is solvent-free, has a simple processing method, has excellent releasability and screen printing suitability, and which does not peel off from a wiring board in a wiring board processing line.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to improve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention

A composition comprising a urethane (meth) acrylate resin (A) obtained from a polyester polyol, a urethane (meth) acrylate resin (B) other than (A), and an ethylenically unsaturated group-containing compound (C). hand,
A screen printing ink composition for a radiation-curable strippable masking material, wherein the glass transition temperature of a resin film layer cured by radiation is 29 ° C. or higher.

When the ink composition of the present invention is used as a UV-curable screen printing ink, a photopolymerization initiator for initiating or promoting a photopolymerization reaction is added to the ink composition. When the present composition is used as an electron beam-curable screen printing ink, it goes without saying that a photopolymerization initiator is unnecessary.

A specific example of the urethane (meth) acrylate resin (A) used in the present invention is obtained by subjecting a diol component selected from ethylene glycol, diethylene glycol, 1,4-butanediol and neopentyl glycol to an esterification reaction with adipic acid. The resulting polyester polyol is reacted with an organic polyisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4-diphenylmethane diisocyanate, and then 2-hydroxyethyl (meth) acrylate, 2-hydroxy Ε-caprolactone adduct of propyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 2-hydroxyethyl (meth) acrylate And urethane (meth) acrylate resin obtained by reacting pentaerythritol tri (meth) hydroxyl group-containing ethylenically unsaturated compounds such as acrylates. This urethane (meth) acrylate resin (A) is reacted with isocyanate groups, preferably 1.1 to 2.0 chemical equivalents, of an organic polyisocyanate at a reaction temperature, preferably 70 to 90 ° C., per one chemical equivalent of a hydroxyl group of a polyol; A urethane oligomer is synthesized, and then obtained by reacting a hydroxyl group-containing ethylenically unsaturated compound with a hydroxyl group, preferably 1 to 1.1 chemical equivalents, at a reaction temperature, preferably 70 to 90 ° C., per 1 chemical equivalent of isocyanate group of the urethane oligomer. be able to.

Examples of the urethane (meth) acrylate resin (B) other than (A) include, for example, polycaprolactone polyol, polycarbonate diol, polytetramethylene glycol, and polyester using the urethane (meth) acrylate resin (A). The organic polyisocyanate described above is reacted with a polyol other than the polyol, such as a polyester polyol, or a mixture of the polyol and the polyol used for synthesizing the urethane (meth) acrylate resin (A). And a compound obtained by reacting a hydroxyl group-containing ethylenically unsaturated compound such as (meth) acrylate. These reactants can be obtained as in the method described above.

The urethane (meth) in the total urethane (meth) acrylate resin in the ink composition of the present invention
The mixing ratio of the acrylate resin (A) is 5 to 45% (parts by weight), and preferably 10 to 30% (parts by weight).
Below this, the printability becomes poor, and above this, the physical properties of the film become weak and the coating film breaks when peeled off, leading to poor suitability as a masking material, which is not preferred.
The total of the component (A) and the component (B) is 45 to 45 in the ink composition.
It is preferably in the range of 50% (parts by weight).

Specific examples of the ethylenically unsaturated group-containing compound (C) used in the present invention include 2-ethylhexyl acrylate and 2-hydroxypropyl (meth) acrylate as monofunctional ethylenically unsaturated group-containing compounds. , Ethyl carbitol acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentanyloxyethyl (meth)
Acrylate, phenoxyethyl (meth) acrylate, nonylphenoxyethyl (meth) acrylate, lauryl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, diethylene glycol (2-ethylhexyl) ether (meth) acrylate, phenylglycidyl ether (meth) ) Acrylate, acryloylmorpholine, etc., and 1,6-hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, neopentyl as a bifunctional ethylenically unsaturated group-containing compound Glycol di (meta)
Alkylene glycol di (meth) acrylates such as acrylates, polyoxyalkylene glycol di (meth) acrylates such as triethylene di (meth) acrylate, tripropylene di (meth) acrylate, and polypropylene glycol di (meth) acrylate, bisphenol A or hydrogen (Meth) acrylates of alkylene oxide adducts of functionalized bisphenol A, epoxy di (meth) acrylates such as ethylene glycol diglycidyl ether di (meth) acrylate and propylene glycol diglycidyl ether di (meth) acrylate. it can. Preferred ethylenically unsaturated group-containing compounds include 2-hydroxypropyl (meth) acrylate, phenylglycidyl ether (meth) acrylate, acryloylmorpholine, and tetraethoxydiacrylate of bisphenol A.

The composition ratio of the ethylenically unsaturated group-containing compound (C) used in the present invention to the ink composition is 5 to 50% (part by weight), preferably 10 to 30%.
(Ratio by weight). If the ratio is less than this, the viscosity of the ink composition increases, which is not preferable in terms of printability.If the ratio is more than this, the film properties of the cured product of the ink composition become weak and the releasability is inferior. Is not preferred.

When photopolymerizing the ink composition of the present invention by irradiating it with ultraviolet light or the like, it is preferable to use a photopolymerization initiator that absorbs light energy to generate radicals. As such a photopolymerization initiator,
For example, acetophenones, benzophenones, Michler's ketones, benzyl, benzoin alkyl ether,
Examples thereof include carbonyl compounds such as benzyl dimethyl ketal and benzoyl benzoate, thioxanthones, and sulfur compounds such as tetramethyltyrium mosulfite. These can be used alone or in combination of two or more. Further, such photopolymerization initiators include, for example, amine compounds such as triethanolamine, P-dimethylaminobenzoic acid isoamyl ester, N, N-diethyl-P-aminobenzonitrile, and tri-n-butylphosphine. Known or common photosensitizers such as phosphorus compounds and chlorine compounds such as hexachloroethane can be used alone or in combination of two or more. The mixing ratio of the photopolymerization initiator and the photosensitizer is preferably 1 to 25 parts by weight based on 100 parts by weight of the composition. If the amount is less than this, the polymerization reaction does not sufficiently occur even when irradiated with ultraviolet rays, and the film properties may be lacking. In addition, even if it is used in a large amount, a profitable effect cannot be obtained. When the ink composition of the present invention is cured with an electron beam, a photopolymerization initiator is not required.

In the ink composition of the present invention, a release agent can be used for the purpose of enhancing the releasability. As the release agent, an organopolysiloxane compound is preferable. Silicone oil such as siloxane, methyl hydrogen polysiloxane, methylphenyl polysiloxane, etc., modified silicone oil modified with alkyl, amino, epoxy, fluorine, carboxyl, alcohol, mercapto, etc., at one or both ends of the molecular chain Examples include silicone macromonomers having a polymerizable functional group. Preferred organopolysiloxane compounds include alcohol-modified silicone oils, alkyl-modified silicone oils, and silicone macromonomers having a (meth) acryloyl group at one terminal polymerizable functional group of the molecular chain. These known and commonly used organopolysiloxane compounds can be used alone or in combination of two or more. These compounds can be used in an amount of 1 to 10 parts by weight, preferably 1 to 4 parts by weight, as needed, based on 100 parts by weight of the composition. If the amount is less than this, the releasability is inferior, and if it is too large, the adhesion to the printed wiring board is inferior and the performance as a masking material may be lacking.

The ink composition of the present invention may contain, in addition to the above components, dyes and pigments, defoamers, leveling agents, light stabilizers (eg, hindered amines), antioxidants, polymerization inhibitors, antistatic agents, zinc stearate and the like. Fillers such as metal soap, calcium carbonate and colloidal silica can be used in combination. The screen printing ink composition for a radiation-curable strippable masking material of the present invention can be obtained by mixing and dissolving each of the above components. To cure the ink composition of the present invention with an electron beam, for example, 10
It is preferable to use an electron beam accelerator capable of irradiating energy of 0 to 5000 eV. Further, in order to cure the ink composition of the present invention by ultraviolet rays, an ultraviolet irradiation device having, for example, a xenon lamp, a high-pressure mercury lamp, or a metal halide lamp is used as a light source. When a high-pressure mercury lamp is used, curing can be performed by irradiating ultraviolet rays with a lamp having a light amount of 80 to 120 W / cm. The ink composition of the present invention needs to have a glass transition temperature of the cured product of 29 ° C. or higher. The film thickness when the ink composition of the present invention is applied to a wiring board or the like for masking is not particularly limited, but is usually 5 to 200 µ, more preferably 40 to 200 µ. Needless to say, the ink composition of the present invention exhibits extremely high thixotropy and is useful for suitability for screen printing, but is also useful for various coating systems, potting systems, and the like.

[0016]

Next, the present invention will be described more specifically with reference to examples. The evaluation in the examples was performed by the following method. In addition, the part in an Example shows a weight part. (1) Printability: Printing was performed on a printed board prepared on a polyimide substrate using a plate made of a 70-mesh polyester screen and a urethane rubber squeegee having a Shore hardness of 60 degrees, and the suitability was evaluated. Printing machine: Minomat Y-40 (manufactured by Mino Group Co., Ltd.) ○ ───Excellent without bubbles on the coating surface △ 泡 Slight bubbles on the coating surface × ───Many bubbles on the coating surface Occurrence (2) Peelability: Difficulty in peeling cured coating from printed board ○ プ リ ン ト Good peeling from printed board △ ───Slightly difficult to peel from printed board × ───From printed board It is difficult to peel off and the film is broken. (3) Thixo ratio: The viscosity of the composition was measured using an R-type viscometer (measured at 25 ° C., 5 rotations, 50 rotations. The thixotropic ratio was 5 rotations / 50 rotations). (4) Film peeling: printing, The cured and masked printed boards are stacked in an oven at 120 ° C. and placed for 5 minutes, then taken out while being stacked and allowed to cool to room temperature. Thereafter, the condition of peeling of the mask material from the printed board when the printed board was released was evaluated. ○ ───Excellent with no peeling of the film from the printed board. Δ─── The film was lifted from the printed board. × ─── The film peeled off from the printed board. (5) Tg point: The glass transition temperature of the cured film was measured. Example of synthesizing urethane (meth) acrylate resin (A)

Synthesis Example 1 Polyester diol of 1,4-butanediol and adipic acid (hydroxyl value 55.9 mgKOH / g) 401.5
, 67.2 parts of hexamethylene diisocyanate, and after heating, reacted at 80 ° C for 10 hours. Next, 46.4 parts of 2-hydroxyethyl acrylate and 0.26 parts of methquinone were charged and reacted again at 80 ° C. for 10 hours. Then, 0.13 parts of di-n-butyltin dilaurate was charged and further reacted at 80 ° C. for 2 hours. Thus, a urethane acrylate was obtained.

Synthesis Example 2 400.0 parts of a polyester diol of ethylene glycol and adipic acid (hydroxyl value 56.1 mg KOH / g),
52.2 parts of tolylene diisocyanate were charged, and after heating, 8
The reaction was performed at 0 ° C. for 10 hours. Next, 23.2 parts of 2-hydroxyethyl acrylate and 0.24 parts of methquinone were charged and reacted again at 80 ° C. for 10 hours. Then, 0.12 parts of di-n-butyltin dilaurate was charged and further reacted at 80 ° C. for 2 hours. Thus, urethane acrylate was obtained.

Synthesis Example 3 Polyester diol of neopentyl glycol and adipic acid (hydroxyl value 55.7 mgKOH / g) 402.9
And 69.6 parts of tolylene diisocyanate. The mixture was heated and reacted at 80 ° C. for 10 hours. Next, 46.4 parts of 2-hydroxyethyl acrylate and 0.24 parts of methquinone were charged and reacted again at 80 ° C. for 10 hours, and then 0.12 parts of di-n-butyltin dilaurate was charged.
The mixture was reacted at a temperature of 2 ° C. for 2 hours to obtain urethane acrylate. Example of synthesizing urethane (meth) acrylate resin (B)

Synthesis Example 4 23.7 parts of neopentyl glycol, polytetramethylene glycol (hydroxyl value 56.3 mg KOH / g) 24
4.2 parts and 155.5 parts of isophorone diisocyanate were charged and reacted at 80 ° C. for 10 hours after heating. Next, 81.3 parts of 2-hydroxyethyl acrylate and 0.25 parts of methquinone were charged and reacted again at 80 ° C. for 10 hours. Then, 0.13 parts of di-n-butyltin dilaurate was charged and further reacted at 80 ° C. for 2 hours. Thus, urethane acrylate was obtained.

Synthesis Example 5 Neopentyl glycol adipate (having a hydroxyl value of 233.
233.8, polytetramethylene glycol (hydroxyl value 56.3 mgKOH / g) 139.
5 parts and 154.8 parts of isophorone diisocyanate were charged and reacted at 80 ° C. for 10 hours after heating. Next, 32.3 parts of 2-hydroxyethyl acrylate and 0.26 parts of methquinone were charged and reacted again at 80 ° C. for 10 hours. Then, 0.13 parts of di-n-butyltin dilaurate was charged and further reacted at 80 ° C. for 2 hours. Thus, urethane acrylate was obtained.

Examples 1 to 5 and Comparative Examples 1 to 3 A screen printing ink for an ultraviolet-curable strippable masking material having the composition shown in Table 1 was prepared, screen-printed on a printed wiring board, and irradiated with an ultraviolet ray or an electron beam. Was irradiated to cure the ink to perform masking. still,
All examples are CI No, PIGMENT BLUE6
4 was added to obtain a blue ink. The coating amount of the printing ink was adjusted so that the film thickness when dried was 70 μm. Examples 1 to 4 and Comparative Examples 1 and 2 were irradiated with ultraviolet rays, and Example 5 and Comparative Example 2 were irradiated with an electron beam. The irradiation method was as follows. UV irradiation: Curing was performed by irradiating twice with a UV irradiation device (GS ASE-20, manufactured by Nippon Battery Co., Ltd.) having a high-pressure mercury lamp of 80 W / cm at a transport speed of 20 m / min. Electron beam irradiation; an electron beam curing device having a dose of 60 Mrad (CB175 / 15/18, manufactured by Eye Graphic Co., Ltd.)
0L) to cure at a transport speed of 20 m / min twice.

Table 1 Ingredients Example Comparative Example 1 2 3 4 5 1 2 3 (A) Synthesis Example 1 Compound 20 20 24 Synthesis Example 2 Compound 15 25 10 25 Synthesis Example 3 Compound 25 30 (B) Synthesis Example 4 Compound 55 40 50 10 Synthesis Example 5 Compound 55 40 40 51 30 (C) R-128 * 1 15 15 10 20 25 21 R-561 * 2 15 10 20 25 R-551 * 3 10 15 10 5 10 4 5 (D) Ir-184 * 4 3 3 3 3 3 3 (E) SF-8416 * 5 3 3 3 3 3 3 3 3 (F) Zinc stearate 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Printability ○ ○ ○ ○ ○ ○ ○ ○ ○ Peeling property ○ ○ ○ ○ ○ ○ ○ ○ Thixotropic property 6.34 7.25 5.18 7.37 6.29 5.82 7.62 4.42 Tg point 43.1 45.8 51.1 31.2 38.3 19.2 24.8 28.5 Film peeling ○ ○ ○ ○ ○ × × △

Note * 1 R-128: KAYARAD R-128 manufactured by Nippon Kayaku Co., Ltd., phenylglycidyl ether acrylate * 2 R-561: KAYARAD R-561 manufactured by Nippon Kayaku Co., Ltd., phenoxyethyl acrylate * 3 R -551: KAYARAD R-551 manufactured by Nippon Kayaku Co., Ltd., tetraethoxydiacrylate of bisphenol A * 4 Ir-184: Irgacure 184, manufactured by Ciba-Geigy, photopolymerization initiator * 5 SF-8416: Toray Dow Corning Alkyl-modified silicone oil

As is evident from the evaluation results in Table 1, the screen printing ink composition for a strippable masking material of the present invention is excellent in printability, releasability, and without film peeling.

[0026]

EFFECT OF THE INVENTION The screen printing ink composition for a strippable masking material of the present invention has a simple processing method, has excellent printability, excellent releasability, and excellent performance in which film peeling does not occur during processing. Suitable for masking material.

Claims (1)

(57) [Claims] 1. A composition comprising a urethane (meth) acrylate resin (A) obtained from a polyester polyol, a urethane (meth) acrylate resin (B) other than (A), and an ethylenically unsaturated group-containing compound (C). And
A radiation-curable screen printing ink composition for a strippable masking material, wherein the glass transition temperature of the resin film layer cured by radiation is 29 ° C. or higher.