JPH01271469A - Ultraviolet-curable ink - Google Patents

Abstract

PURPOSE:To obtain an ultraviolet-curable ink improved in a tack-free time and the hardness, etc., of a cured resist and being usable in screen printing by mixing an ultraviolet-curable resin with a specified photopolymerizable monomer and a photopolymerization initiator, a colorant and additives. CONSTITUTION:A product (i) of the Diels-Alder reaction of an (alkyl-substituted) cyclopentadiene with maleic anhydride is monoesterified with a hydroxyalkyl (meth)acrylate (ii) to obtain a (meth)acryloxy endomethylenetetrahydrophthalate derivative (a) of the formula (wherein R<1> is H or an alkyl, R<2> is H or CH3, and n is 1-10). A low-MW ultraviolet-curable resin (A) which is preferably an air-drying unsaturated polyester of an MW of 250-1500, optionally having an allyl group, is mixed with a photopolymerizable monomer (B) comprising 2-80wt.%, based on the total of components A and B, component (a) and, optionally, another monomer (b), in an amount to give a weight ratio of A to B of 5-70:95-30, a photopolymerization initiator (C), a colorant (D) and other ink additives (E).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultraviolet curing ink, particularly an etching resist ink for printed wiring boards produced by screen printing.

Conventional technology Ultraviolet curing ink does not require thermal energy for curing, has an extremely fast curing speed, and does not contain solvent components, so it has advantages in terms of productivity, downsizing of equipment, energy saving, pollution prevention, and safety. It is advantageous and demand is rapidly increasing.

On the other hand, with the development of the electronics industry, the amount of ink used for printed wiring boards is also increasing. Printing methods using ink for printed wiring boards include offset printing and screen printing, with screen printing being the mainstream.

Against this background, attempts have been made to use ultraviolet curing inks as etching resist inks for printed wiring boards using screen printing methods, and various inks are already commercially available.

JP-A-51-2503 discloses an ink made of saturated or unsaturated polyester and hydroxyethyl (meth)acrylate;
No. 69 discloses that a copolymer obtained by reacting an aromatic vinyl compound-unsaturated dibasic acid copolymer with hydroxyethyl (meth)acrylate, an ethylenically unsaturated compound, a photopolymerization initiator, and an ink. There is a disclosure regarding an ultraviolet curable ink containing an agent.

Problems to be Solved by the Invention However, when the currently commercially available ultraviolet curable ink is used as an etching resist ink for printed wiring boards by screen printing, the tack-free time, hardness of the cured resist, and the hardness of the cured resist are limited. It is difficult to balance the three properties of alkaline removability, for example, if the tack-free time is fast and the hardness of the cured film is high, the removability of the cured resist with the alkaline remover will be insufficient, and the alkali peelability of the cured resist will be difficult. Those with good peelability with liquid have problems such as slow tack-free time and low hardness of the cured resist.

The above-mentioned Japanese Patent Application Publication No. 51-2503 and Japanese Patent Application Publication No. 57-85
The ultraviolet curable ink disclosed in Japanese Patent No. 869 still has room for improvement in terms of the balance of the above three properties.

In view of these circumstances, the present invention aims to provide fast tack-free time, high hardness of the cured resist, and ease of peeling and removability of the cured resist with an alkaline stripper when the screen printing pattern is cured by irradiating ultraviolet rays. The purpose was to provide a good ultraviolet curable ink.

Means for solving the problem, that is, the ultraviolet curable ink of the present invention comprises a low molecular weight ultraviolet curable resin (A), a photopolymerizable monomer (B), a photoinitiator (C), a colorant CD), and others. and at least a part of the photopolymerizable monomer (B) has the formula (wherein R is H or an alkyl group, R is H or CH
3, n is an integer of 1 to 10).

The present invention will be explained in detail below.

As the low molecular weight ultraviolet curable resin (A), unsaturated polyester, epoxy acrylate, urethane acrylate, polyester acrylate, polyol acrylate, polyether acrylate, acrylate alkyd, melamine alkyd, etc. are suitably used. All of these resins are commercially available, so they can be easily obtained, and they can also be synthesized. Of these resins, unsaturated polyester, epoxy acrylate, and urethane acrylate will be further explained.

Examples of unsaturated polyesters include maleic acid or its anhydride, tylenically unsaturated dibasic acids such as itaconic acid and fumaric acid, or saturated carboxylic acids such as phthalic acid, and ethylene glycol.

Products obtained by condensation reaction with polyhydric alcohols such as diethylene glycol, triethylene glycol, neopentyl glycol, pentaerythritol, trimethylolethane, trimethylolpropane, and hydroxylpentadiene, or ethylenically unsaturated dibasic acids or Furthermore, along with saturated carboxylic acids such as phthalic acid and polyhydric alcohols, pentaerythritol triallyl ether and pentaerythritol diallyl ether.

Trimethylolpropane diallyl ether, trimethylolpropane monoallyl ether, trimethylolethane diallyl ether, trimethylolethane monoallyl ether, glycerin diallyl ether, glycerin monoallyl ether, tetramethylolcyclohexanol diallyl monocrotyl ether, hexamethylolmelamine diallyl dichloro Products obtained by condensation reaction of allyl compounds such as thyl ether, hexanetriol diallyl ether, pentaerythritol diallyl crotyl ether, tetramethylolcyclohexanol triallyl ether, tetramethylolcyclohexanone diallyl ether, and hexamethylolmelamine tetraallyl ether. can be given.

Epoxy acrylates include bisphenol A epoxy resin, bisphenol F epoxy resin, halogenated bisphenol epoxy resin, resorcinol epoxy resin, novolak epoxy resin, alicyclic epoxy resin, dicarboxylic acid-modified epoxy resin, glycerin glycidyl ether, Products obtained by adding compounds such as acrylic acid, methacrylic acid, phthalic anhydride-hydroxyacrylate adducts, and succinic anhydride-hydroxyacrylate adducts to glycidyl groups such as epoxidized soybean oil and triglycidyl isocyanurate. can give.

As the urethane acrylate, tolylene diisocyanate, xylylene-1,4-diisocyanate, 1,6
Examples include those obtained by reacting a polyisocyanate compound such as -hexamethylene diisocyanate with a polyhydric alcohol such as trimethylolpropane, glycerin, or pentaerythritol, and then adding hydroxyalkyl (meth)acrylate to the remaining Nco group.

The molecular weight of the ultraviolet curable resin (A) is preferably from 250 to 1,500; if the molecular weight is too small, the hardness will be low, the film-forming properties will be poor, and it will be impractical. On the other hand, if the molecular sacs are too large, the viscosity will increase, resulting in poor printability and poor resist peelability. Furthermore, in order to lower the viscosity, it is necessary to increase the proportion of the momentum monomer component, which impairs printability and causes bleeding.

Among the ultraviolet curable resins (A) exemplified above, air-drying unsaturated polyesters having an allyl group and having a molecular weight of 250 to 1,500 are particularly preferred since the tack-free time is short.

Nanatsuma-B (Derivative represented by formula (I)) In the present invention, (meth)acryloxyendomethylenetetrahydrophthalate represented by the above formula (I) is used as at least a part of the photopolymerizable monomer (B). Use derivatives.

This derivative is obtained by monoesterifying 3,6-nindomethylene-Δ-atophhydrophthalic anhydride, which is a Diels-Alter reaction product of cyclopentadiene or its alkyl substituted product with maleic anhydride, with hydroxyalkyl (meth)acrylate. Manufactured by.

Specific examples of the above derivatives include (meth)acryloxymethylendomethylenetetrahydrophthalate, (meth)
Acryloxyethyl endomethylene tetrahydrophthalate, (meth)acryloxypropyl endomethylene tetrahydrophthalate, methyl (meth)acryloxymethyl endomethylene tetrahydrophthalate, methyl (meth)acryloxyethyl endomethylene tetrahydrophthalate, methyl (meth)acryloxypropyl Endomethylenetetrahydrophthalate, ethyl (
meth)acryloxymethylendomethylenetetrahydrophthalate, ethyl (meth)acryloxyethylendomethylenetetrahydrophthalate, ethyl (meth)
Examples include acryloxypropyl endomethylene tetrahydrophthalate.

<Other photopolymerizable monomers (B)) Photopolymerizable monomers (B) other than the derivatives represented by formula (I)
) as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
-Hydroxybutyl (meth)acrylate, phenoxyethylene glycol (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate,
Hydroxyl group-containing (meth)acrylates such as 2-(meth)acryloyloxy-2-hydroxypropyl phthalate and 3-chloro-2-hydroxypropyl (meth)acrylate: ethylene glycol monomethyl ether (meth)acrylate, ethylene glycol monoethyl ether (meth)acrylate, diethylene glycol monomethyl ether (meth)acrylate, diethylene glycol monoethyl ether (meth)acrylate, diethylene glycol mono-n-propyl ether (
Mono- or polyethylene glycol monoalkyl ether (meth)acrylates such as meth)acrylate, triethylene glycol monoethyl ether (meth)acrylate; polyhydric alcohol mono(meth)acrylate such as polyethylene glycol mono(meth)acrylate, glycerin mono(meth)acrylate; ) acrylate; half (meth)acrylate of phthalic acid or phthalic acid derivatives such as ethyl (meth)acryloxyphthalate, ethylene glycol (meth)acrylate phthalate, ethylene glycol (meth)acrylate hydroxyphthalate;
Half (meth)acrylates of succinic acid such as ethylene glycol (meth)acrylate succinate: phenoxyethylene glycol (meth)acrylate, N-methylol (meth)acrylamide, diaseptane (meth)acrylamide, dimethyl (meth)acrylamide,
(meth)acrylamide; dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate; lauryl (meth)acrylate; styrene, vinyltoluene; N-vinylpyrrolidone: 2-(meth)acryloyloxyethyl acid phosphate; Examples include functional monomers.

Along with these monofunctional additives, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,
Butylene glycol di(meth)acrylate, neopentyl glycol di(meth)7 acrylate, 1゜6-hexane gelicoldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin di(meth)acrylate,
meth)acrylate, pentaerythritol di(meth)
Acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 2,2-bis (4-(meth)acryloki sidiethoxyphenyl)propane, 2,2-bis(4-(
meth)acryloxypolyethoxyphenyl)propane,
2-hydroxy-3-(meth)acryloyloxypropyl (meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, 1,6-hexamethyl diglycidyl ether di( Polyfunctional monomers such as meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, and glycerin polyglycidyl ether poly(meth)acrylate can also be used in combination.

AB The blending ratio of the ultraviolet curable resin (A) and the photopolymerizable 7-mer (B) is 5:95 to 70:30, especially 10:30 by weight.
:90~50 : Set in the range of 50. Too little (A) or too much (B) will lead to a decline in film-forming properties and printability.
Too much of A) and too little of (B) will lead to an increase in viscosity and impair printability, as well as poor resist peeling.

Then, ultraviolet curable resin (A) and photopolymerizable monomer (
The proportion of the derivative of formula (I) in the total amount of B) is 2
-80% by weight, especially 5-60% by weight. Whether the proportion of the derivative is less than or greater than this range, the desired objectives are achieved, namely, the tack-free time is fast, the hardness of the cured resist is high, and the peelability of the cured resist with an alkaline stripper is good. This objective cannot be fully achieved.

Examples of the photopolymerization initiator (C) include benzoin,
Benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, benzoin phenyl ether, benzyl diphenyl disulfide, dibenzyl, diacetyl, anthraquinone, naphthoquinone, benzophenone, p, p'-bis(dimethylamino)benzophenone , bivaloin ethyl ether, benzyl ketal, benzyl dimethyl ketal, 1.1-
Dichloroacetophenone, pt-butyldichloroacetophenone, 2-chlorothioxanthone, 2-methylthioxanthone, 2゜2-jethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone,
2,2-dichloro-4-phenoxyacetophenone, dimethylaminoacetophenone, Michler's ketone, phenylglyoxylate, α-hydroxyisobutylphenone, dibenzosparone, benzophenone amine type, 1
-(4-isopropylphenyl)-2-hydroxy-2
-Methyl-1-propanone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, tribromophenylsulfone, tribromomethylphenylsulfone, etc., and these are used in appropriate combinations. be able to.

The blending ratio of the photopolymerization initiator (C) is as follows:
0.5 based on the total amount of A) and photopolymerizable monomer (B)
-20% by weight, especially 1-10% by weight is suitable.

As the colorant (D), various dyes and pigments including phthalocyanine, induthrone, azo, carbon black, and titanium oxide are used. Considering that it is an ultraviolet curable ink, care should be taken to select one with good ultraviolet resistance.

Ink E Other ink additives include thixotropic regulators, leveling agents, antifoaming agents, thermal polymerization inhibitors, solubility promoters for dilute alkalis, and extenders (calcium carbonate, talc, precipitated barium sulfate, etc.) ), plasticizers, solvents, etc., and an appropriate one is selected from among various additives conventionally used for inks. Generally, printing inks are made by finely dispersing colorants in a vehicle, but these additives may not be enough to fully demonstrate the performance of the printing ink, so these additives are added.

Ink The ultraviolet curable ink of the present invention is prepared by uniformly mixing the above-mentioned components simultaneously or in any order. Mixing is often performed using a premixer or a mixer such as a Miki roll.

An ink containing the photopolymerization initiator (C) can also be prepared separately and mixed at the time of use.

The viscosity of the ink is 100-2 for screen printing.
000. In particular, 150 to SOO poise (25°C) is suitable.

As the shell printing method, a screen printing method is suitably employed, and an offset printing method is also employed in some cases.

When screen printing is performed on a copper-clad board or a flexible board for a printed wiring board, a screen made of polyester, nylon, stainless steel, or silk and having a mesh size of about 100 to 500 is used. Among these screens, polyester screens are the most popular.

The film thickness of the printed pattern is often %5 to 100IL.

Exposure after one-prong printing is performed by ultraviolet irradiation, and the light source used at this time is a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a Cannon lamp, a metal halide lamp, a chemical lamp, a black light, or the like.

After irradiation with ultraviolet rays, heating can be performed as necessary to ensure complete curing.

After the make exposure, the parts of the substrate other than those covered by the hardened resist are etched or plated.

When an etching method is employed, etching is carried out according to a conventional method using an etching solution such as a ferric chloride aqueous solution or a cupric chloride aqueous solution.

When the plating method is employed, a plating pretreatment agent such as a degreasing agent and a soft etching agent is used for pretreatment, and then plating is performed using a plating solution.

Peeling and removal of the hardened resist after resist etching or plating is performed using an alkaline stripping solution.

As the alkaline stripper, an aqueous solution of sodium hydroxide or potassium hydroxide with a weight of 1 to 5% is usually used.
This is heated to about 40 to 60°C, and the cured resist is peeled off by spraying or dipping.

Furthermore, the ultraviolet curable ink of the present invention is particularly useful as an etching resist ink for printed wiring boards by screen printing.

Function and Effects of the Invention In addition to the advantages of conventional ultraviolet curable inks (improved productivity, compact equipment, energy saving, pollution prevention, and safety), the ultraviolet curable ink of the present invention has a strong reputation in the industry. The following three properties are desired: ■Fast tack-free time when curing the printed pattern by irradiating it with ultraviolet rays, ■High hardness of the cured resist, and ■Alkali-free cured resist that is no longer needed. At the same time, it has good peeling and removability using a stripping solution.

Therefore, the present invention greatly contributes to this industry.

Example Next, the present invention will be further explained with reference to Examples.

Hereinafter, "part" and "1%" are expressed on a weight basis.

The following materials were prepared for the experiment.

A-1 (unsaturated polyester) 0.7 mol of maleic anhydride, 0.3 mol of phthalic anhydride,
1.01 mol of propylene glycol and 0.25 mol of trimethylolpropane diallyl ether were placed in a 470 round bottom flask, heated at 170° C. for 5 hours with stirring, and then under reduced pressure of 10 tsHg.

The reaction was continued at 150° C. for 30 minutes, and when the acid value of the resin reached 40 parts gKOH/g, the reaction was stopped to obtain an unsaturated polyester. The molecular weight of the obtained resin was 1200.

A-2 (Epoxy acrylate) 256 parts of bisphenol A type epoxy resin with an epoxy equivalent of 174, 180 parts of methacrylic acid, trimethylbenzylammonium chloride Fo, 2s, and 0.05 part of hydroquinone monomethyl ether were charged into a flask.
The epoxy acrylate obtained by reacting at 100° C. for 6 hours had a molecular weight of 520.

A-3 (Urethane acrylate) 140 parts of tolylene diisocyanate, 7 parts of trimethylolpropane, and 35 parts of propylene glycol were charged into a flask and reacted at 90°C for 5 hours. Then, this product was added with hydroxyethylmethac+) L/ -door 2f
Jr. and 0.03 part of hydroquinone monomethyl ether were added and reacted at 60° C. for 6 hours to obtain urethane acrylate, which had a zero molecular weight of 980.

Nanatsuma-B (Derivative represented by formula (I)) -t Ethyl MethacryloxymethylendomethylenetetrahydrophthalateMethacryloxyethylendomethylenetetrahydrophthalateMethyl acryloxymethylendomethylenetetrahydrophthalate (Other photopolymerizable monomers) Ethylmethacryloxy Phthalate Phenoxyethylene glycol acrylate Hydroxypropyl acrylate Ethylene glycol methacrylate Phthalate-t 2-Hydroxy-2-methyl-1-phenylpropane-
1-1 Mixture 1 Color Blood 2 1 Niphthalocyanine Blue Mixture E Examples 1 to 5 (Blending recipe and preparation of ink) After premixing each component according to the following recipe, a three-roll mixer was used three times. Through this process, the ultraviolet curable ink of Example 1 was prepared.

IE-153, 5 parts Total 100 parts Also, when using A-27 parts and b-111 parts instead of A-110 parts and b-18 parts (Example 2), A-110
Ultraviolet curable inks were prepared using A-31 parts and C-23 parts in place of A-31 parts and C-13 parts (Example 3).

Furthermore, in place of b-18 parts, b-28 parts were used (Example 4), b-38 parts were used (Example 5)
), UV-curable inks were prepared for each of them.

25°C of inks in Examples 1.2.3, 4 and 5
The viscosity of 200 poise, 180 poise, 250 poise, and 200 poise, respectively, was measured using a B-type rotational viscometer.
The fist was 190 poise (Screen printing on copper clad substrate) Using a 250 mesh polyester screen, the ultraviolet curable ink prepared above was screen printed on the copper surface of the copper clad substrate.

(Exposure, tack-free time, hardness) (Exposure, tack-free time, hardness) Using an exposure machine with an 80% 1/c ■ high-pressure mercury lamp as the light source, the irradiation distance was 10 cm, and the conveyor speed was 6 ■/in.
UV rays were irradiated under these conditions, and the tack-free time of each was measured.

At the same time, the hardness (pencil hardness) of the cured resist was also measured.

<Etching> For etching after exposure, use a cupric chloride acidic etching solution at a solution temperature of 50°C and a spray pressure of 1.5kg/am.
The test was carried out for 90 seconds.

<Peeling and Removal of Hardened Resist> Condition 1 The cured resist was peeled off using a 3% aqueous sodium hydroxide solution at 50° C. and a spray pressure of 1.5 kg/cm2, and the peeling and removal time at this time was measured.

Comparative Example 1 In the formulation of Example 1, b-t was omitted and B-t was added instead.
A similar experiment was conducted except that 48 parts were used.

Comparative Example 2 The same experiment as in Examples 1 to 5 was conducted except that 37 parts of A-328 parts of B-and 5 parts of trimethylolpropane triacrylate were used.

The results of Examples 1 to 5 and Comparative Examples 1 to 2 are shown in Table 1.

Table 1

Claims (5)

[Claims] 1. It consists of a low molecular weight ultraviolet curable resin (A), a photopolymerizable monomer (B), a photopolymerization initiator (C), a colorant (D) and other ink additives (E), and the photopolymerizable At least a part of the monomer (B) has the formula ▲A mathematical formula, a chemical formula, a table, etc.▼(I) (However, R^1 is H or an alkyl group, R^2 is H or CH_3, and n is an integer from 1 to 10. An ultraviolet curable ink that is a (meth)acryloxyendomethylenetetrahydrophthalate derivative represented by (an integer). 2. Ultraviolet curable resin (A) and photopolymerizable monomer (B)
The proportion of the derivative of formula (I) in the total amount of
The ultraviolet curable ink according to claim 1, which is % by weight. 3. The low molecular weight ultraviolet curable resin (A) is a resin with a molecular weight of 250 to 1500 selected from the group consisting of unsaturated polyester, epoxy acrylate, urethane acrylate, polyester acrylate, polyol acrylate, polyether acrylate, acrylate alkyd, and melamine alkyd. The ultraviolet curable ink according to claim 1. 4. The ultraviolet curable ink according to claim 1, wherein the low molecular weight ultraviolet curable resin (A) is an air-drying unsaturated polyester having an allyl group and a molecular weight of 250 to 1,500. 5. The ultraviolet curable ink according to claim 1, which is an ink for screen printing.