JPS6123822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultraviolet curable ink composition, and particularly to a flame-retardant ultraviolet curable screen ink composition useful as a protective film for printed wiring.

In recent years, UV-curable inks have become popular in order to streamline the drying process, and in the printed wiring field, UV-curable screen inks are replacing etching resists, solder resists, protective films, etc. that were traditionally dried with hot air. It is active.

On the other hand, depending on the application, printed wiring boards range from hard plate-like materials such as conventional glass fiber-reinforced epoxy resin, unsaturated polyester, and phenolic resin laminates to flexible film-like materials such as polyester film, heat-resistant Vinyl chloride film, polyimide film, polyamide film, etc. have come to be used as base materials.

The inventors of the present invention have carried out studies to develop a protective ink with excellent performance, especially for such flexible substrates. , secondary physical properties,
Furthermore, we have succeeded in developing an ultraviolet curable screen ink composition that has excellent flame retardancy and printability, which have been strongly demanded recently. The gist of the present invention is as follows: (A) A compound having two or more acroyl groups and two or more urethane bonds in one molecule obtained by reacting a polyisocyanate compound, a polyhydroxy compound, and a hydroxyacrylate.
40-80% by weight, (B) acrylic monomer 5-30% by weight, (C) phosphoric acid (meth)acrylate
(D) a flame retardant 5-40% by weight; and (E) a photopolymerization initiator 0.1-10% by weight.

Specific examples of compounds used in the ultraviolet curable ink composition of the present invention are as follows. first
Component (A) is a compound having two or more acroyl groups and two or more urethane bonds in one molecule, which is obtained by reacting a polyisocyanate compound with a polyhydroxy compound as a chain extender and a hydroxyacrylate. , as the polyisocyanate compound, tolylene diisocyanate,
Examples include xylylene diisocyanate, hexamethylene diisocyanate, 4,4' diphenylmethane diisocyanate, lysine isocyanate, isophorone diisocyanate, dimer acid diisocyanate, trimethylhexane diisocyanate, and polyisocyanates that are reactants of these and low-molecular polyols. Can be used. Polyhydroxy compounds that are chain extenders include neopentyl glycol, 2, 2, 4 trimethyl 1,
3 pentanediol, 1.6 hexanediol,
Triethylene glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, bisphenol A, hydrogenated bisphenol A, adducts of hydrogenated bisphenol A and ethylene oxide, propylene oxide, polycaprolaftertone diol, terminal or side chain Examples include low-molecular polyester polyols having hydroxyl groups.

In addition, as hydroxyacrylate, 2-
Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-
(2-ethylhexyloxy)propyl acrylate and the like are used.

Component (A) is a component that provides the basic physical properties of the ink film, and is a component that has good curing properties when exposed to ultraviolet rays in the air, and also provides flexibility and toughness to the film.

The amount of component (A) used is preferably 40 to 80% by weight; if it is less than 40%, the flexibility of the film will be poor, and if it is more than 80%, (A)
Since the viscosity of the components themselves is high, the viscosity of the ink composition becomes too high, resulting in poor printability, which is not preferable.

The acrylic monomer, component (B), is used as a reactive diluent, but it must have low volatility and not have a negative effect on curability or film properties. Acrylic monomers such as acrylate, benzyl acrylate, cellosolve acrylate, 2-ethylhexyl acrylate, and epoxystearyl acrylate can be used, among which tetrahydrofurfuryl acrylate, cellosolve acrylate, and 2-ethylhexyl acrylate give very good results.

The amount of component (B) to be used is preferably 5 to 30%, and if it is less than 5%, the viscosity of the composition will not be reduced sufficiently, and if it is more than 30%, the curability will decrease and the toughness of the film will also decrease, so it is not desirable. do not have.

As the phosphoric acid (meth)acrylate which is component (C), a compound represented by the following formula is used.

(R is H or CH ₃ , m is 1, 2, 3, n is 0,
1,2 m+n=3) Specifically, a condensation product of 1 mole of phosphoric acid and 3 moles of hydroxyethyl acrylate or hydroxypropyl acrylate is suitable.

Component (C) is an adhesion improver to the copper that forms printed wiring, and adding a small amount will significantly improve adhesion, but if it is added in excess, the curing properties and water resistance of the film will decrease. , the preferred range is 0.1 to 10
%.

Next, (D) the flame retardant must be selected taking into consideration the ultraviolet curability of the ink composition, the flexibility and toughness of the film, and the printability of the ink, including phosphoric acid esters, halogen compounds, phosphorus-halogen compound,
When we examined a wide range of compounds, including inorganic compounds, either singly or in combination, we found that phosphorus-based compounds tend to reduce curing properties and film properties;
In addition, inorganic compounds such as antimony trioxide have drawbacks such as poor UV transmittance and significantly inhibit hardening of the inside of the film, but halogen compounds have been found to be relatively good. In particular, brominated aromatic compounds such as hexabromobenzene, decabromophenyl, and decabromodiphenyl ether provide the best performance, have a large flame retardant effect on component (A), and have little to no curability. Moreover, these compounds are fine powders, and when dispersed in a composition, they have the effect of eliminating the spinnability, which is a drawback of component (A), and therefore improve the suitability for screen printing. Particularly desirable. In some cases, some lower brominated versions of these brominated aromatic compounds may also be used. The amount of flame retardant (D) used is 5 to 40% in terms of flame retardancy and film flexibility.
% is appropriate.

The photopolymerization initiator (E) may be used alone or in combination, and specifically includes benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzylbenzophenone, chloranthraquinone, Examples include 2.2-diethoxyacetophenone and a mixed system of benzophenone and tertiary amine.

The amount of (E) photoinitiator contained in the ink composition is
It is desirable to use it in the range of 0.1 to 10% in terms of curing speed and film properties.

In order to further improve adhesion, flexibility, corrosion resistance, etc., a thermoplastic resin is mixed into the ultraviolet curable ink composition obtained in this way. Examples of thermoplastic resins include: , acrylic copolymers, vinyl chloride-vinyl acetate copolymers, polyesters, polyamides, epoxy resins, etc.

Further, in order to improve printability as a screen ink or for coloring, ordinary fillers, antifoaming agents, repelling agents, anti-threading agents, dyes, pigments, etc. are also mixed.

As the light source used for curing the ultraviolet curable ink composition of the present invention, lamps with a radiation wavelength of 200 to 450 mμ, such as low pressure mercury lamps, high pressure mercury lamps, arc lamps, xenon lamps, and gallium lamps, are effective.

The method of the present invention will be explained in detail with reference to Examples below. In the examples, parts mean parts by weight.

Example 1 Polyether (ADEKA P-700, manufactured by Asahi Denka Co., Ltd.)
730 parts of xylylene diisocyanate, 280 parts of 2-hydroxyethyl acrylate, 0.2 parts of n-butyltin dilaurate, and 0.2 parts of hydroquinone monomethyl ether in a reaction vessel at 70°C.
The mixture was reacted for a period of time to obtain a urethane acrylate compound.

65 parts of this urethane acrylate compound, 10 parts of carbitol acrylate, 20 parts of decabromodiphenyl, 5 parts of trismethacryloxyphosphate
1 part of cyanine blue, 1 part of antifoaming agent, and 3 parts of benzoin butyl ether were kneaded using three rolls to obtain an ultraviolet curable screen ink composition with good printability.

The above ultraviolet curable screen ink composition is printed on a copper printed wiring board based on polyimide film using a 150 mesh screen,
Using an ultraviolet irradiation device equipped with two 200W/in high-pressure mercury lamps, irradiation was carried out at a conveyor speed of 5m/min.
A protective coated printed wiring board with excellent adhesion, flexibility, flame retardancy, and electrical properties was obtained.

Example 2 40 parts of the same urethane acrylate compound used in Example 1, 10 parts of tetrahydrofurfuryl acrylate, 30 parts of decabromodiphenyl ether
1 part, trisacryloxyphosphate 5 parts, epoxy resin (EPON1001, manufactured by Ciel) 15 parts, calcium carbonate 5 parts, cyanine green 1 part, antifoaming agent 1 part and diethoxyacetophenone 2 parts were kneaded and printed. A UV-curable ink composition with good suitability was obtained.

When the above ultraviolet curable ink composition was printed on a copper printed wiring board based on polyester film in the same manner as in Example 1 and cured, insulation protection with good adhesion, flexibility, and flame retardancy was obtained. A printed wiring board was obtained.

Claims (1)

[Scope of Claims] 1 (A) Compound having two or more acroyl groups and two or more urethane bonds in one molecule obtained by reacting a polyisocyanate compound with a polyhydroxy compound and a hydroxyacrylate 40 to 80 weight %, (B) Acrylic monomer 5-30% by weight, (C) Phosphoric acid (meth)acrylate
An ultraviolet curable ink composition whose main component is a mixture consisting of 0.1 to 10% by weight, (D) 5 to 40% by weight of a flame retardant, and (E) 0.1 to 10% by weight of a photopolymerization initiator. 2 (B) The ultraviolet curing method according to claim 1, wherein the acrylic monomer is one or a mixture of two or more selected from tetrahydrofurfuryl acrylate, benzyl acrylate, cellosolve acrylate, 2-ethylhexyl acrylate, and epoxystearyl acrylate. Type ink composition. 3 (D) The ultraviolet curing method according to claim 1, wherein the flame retardant is one or a mixture of two or more selected from hexabromobenzene, decabromodiphenyl, and decabromodiphenyl ether. Type ink composition.