NL8702942A - Photosensitive coating composition and method for preparing a photosensitive polymer. - Google Patents

Description

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873078 / Ba / MW

Photosensitive coating composition and method for preparing a photosensitive polymer.

This invention relates to a photosensitive coating composition.

More particularly, the invention relates to a photosensitive resin composition for forming a protective coating layer with exceptional characteristics which can be used either alone to provide a photosensitive tacky layer; or can be combined with a variety of other types of ingredients such as a cross-linking agent to increase cross-linking density, a resin to remove tackiness, or even another photosensitive component to increase sensitivity to light.

Thus, the applications of the present photosensitive coating material include photo-covering applications such as plating coaters, etch coaters, and solder masks.

Solder mask means are used to manufacture printed circuit board wires. The solder mask function is essentially to prevent solder bridges, maintain electrical insulation between conductors preventing conduction between the solder areas and prevent corrosion of a bare copper conductor. It is also desirable to have photosensitive solder masks capable of holding an image that can be used as a blueprint on which the solder is applied. Due to the desirability of increasing the wiring density, it is desirable to use a solder mask with an accurate resolution and particularly good electrical insulation properties. The present photosensitive composition can provide these advantages.

Solder masks are known per se and are described in U.S. Patent 4,499,163, which describes a photosensitive resin composition. 8 7 0 2 3 41 '-2-urethane diacrylate or dimethacrylate, a linear polymeric compound having a glass transition temperature between about 40 ° C and 150 ° C, and a sensitizer that forms free radicals upon irradiation with high energy radiation.

The described linear polymeric compound includes the vinyl series linear, polymers or copolymers such as, for example, polymers made from vinyl monomers including methyl methacrylate, butyl methacrylate, methyl styrene, vinyl toluene and the like. The free radical generating sensitizer includes, for example, substituted and unsubstituted polynuclear quinones.

Another light-curable urethane-acrylate resin composition suitable also described as useful as permanent protective layers is described in U.S. Patent 4,587,201. The composition as described therein utilizes a urethane acrylate resin composed of polybutadiene polymer. This resin is combined with a photopolymerization initiator to form the permanent protective material.

20 Most photosensitive solder masks lack the ability to be developed in an aqueous solution. This necessitates the use of organic solvent development solutions. The use of such organic solvents has become undesirable due to environmental rules for solvent emission control.

Another drawback found in solder masks employing organic developer solutions is the residual sensitivity of the final product to organic solvents such as methylene chloride. Moreover, in certain applications of the product, such sensitivity is undesirable.

It is therefore desirable to develop a photosensitive solder mask coating layer compositions that can be developed in aqueous solution and that are resistant to organic solvents such as methylene chloride. The object of the present invention is to provide such a coating composition. It is also an object of the present invention to provide a solder mask coating composition that can be removed. 87 0 2 8 *? {* -3- with commercially available alkaline strippers.

The above-described parts are achieved with the photosensitive composition according to the invention which is characterized in that it comprises: an ultraviolet radiation-sensitive polymer selected from the group consisting of: a carboxylated urethane dimethacrylate, a carboxylated urethane diacrylate, a carboxylated urethane triacrylate, and a carboxylated urethane triacrylate -10 methacrylate; wherein said polymer sensitive to UV radiation is formed by condensing a reaction mixture consisting of component (a): a diisocyanate of 6-18 carbon atoms, component (b): a carboxylic acid polyol of the formula II? 15 wherein x may be an integer from 2-5, and wherein Rg is a linear or branched, saturated, unsaturated or aromatic, hydrocarbon group of 2-29 carbon atoms, and component (c) is a hydroxyalkyl (meth) acrylate, the alkyl group of 2-28 carbon atoms; provided that component (a) is present in an amount of from about 30 to about 80% by weight of the total amount of the reaction mixture; component (b) is present in an amount of from about 5 to about 45% by weight of the total amount of the reaction mixture 25 with a minimum of about 0.3 milliequivalents of acid per gram of the total amount of reaction mixture, and component (c ) is present in an amount of from about 5 to about 50% by weight of the total reaction mixture with a minimum amount of 0.5 milliequivalents of acrylate per gram of the total amount of the reaction mixture.

The photosensitive resin compositions as described herein have extremely good resolution, flexibility, metal adhesion, solvent resistance, high temperature resistance, and electrical insulation properties.

Specific embodiments of the present composition form a highly viscous, photosensitive degree, 3 r f 'i / f i. R * -4 material useful as an additive for compositions requiring both thickening and the addition of a photosensitive coating material. In this way, the present photosensitive materials perform a double role, both as a thickener and a photosensitive photosensitive additive. These embodiments of the present compositions are therefore useful photosensitive light-curable thickeners for materials such as paints, inks and the like.

A light curable coating composition comprises a UV sensitive compound selected from: carboxylated urethane diacrylate, carboxylated urethane triacrylate, carboxylated urethane dimethacrylate and carboxylated urethane trimethacrylate. This group is hereinafter referred to as carboxylated urethane di- (and / or) tri (meth) acrylate. It will be clear that (meth) acrylate is meant here to be acrylate and / or methacrylate.

These carboxylated urethane di- and / or tri (meth) -20 acrylates are prepared from acidified parts providing the carboxyl group. These compositions are prepared by condensing a diisocyanate, a carboxylic acid polyol, and a hydroxyalkyl (meth) acrylate. The carboxylic acid polyol must be present in an amount necessary to provide at least about 0.3 milliequivalents of acid per gram of the pooled amount of the total amount of reactants; abbreviated herein as meq / g of TR (usually the total of the reactants is the diisocyanate, carboxylic acid polyol, and hydroxyalkyl (meth) -30 acrylate). In order to obtain an appropriate photosensitivity level in this product, the hydroxyalkyl (meth) acrylate must be used in a minimum amount of about 0.5 milliequivalents per gram of the combined amount of the diisocyanate, carboxylic acid di-35 or triol and hydroxyalkyl (meth) acrylate.

The present invention encompasses a variety of embodiments obtained by combining the above-mentioned coating composition with other specifically selected ingredients. Such constituents, selected p “7 t. 1 é W ƒ V '£. - "," a, "IJ - 1 ~" · - | 4.

-5- to provide or enhance a specific ability or property include: a binder, a cross-linking agent, dyes, pigments, thermopolymerization inhibitors, and additives to enhance the coating properties.

The present photo-curable coating composition includes the carboxyl moiety, which changes the organic solvent-loving nature of the urethane (meth) acrylate polymer. As a result, the present coating compositions become more organic solvent repellent and thus resistant to organic solvents such as methylene chloride. Furthermore, these carboxylated photosensitive polymers can be mixed in large amounts with other water-loving binders and cross-linking agents. In addition, the introduction of the carboxyl moiety renders the present coating composition soluble or swellable in aqueous alkaline solutions (pH greater than 7.5) until exposed to UV light.

Advantageously, when the present compositions are used to provide a coating or solder mask that can be cured with light, the developing step can be advantageously carried out in aqueous alkaline solutions. Thus, it can be noted that although incorporation of the carboxyl part, the nature of the urethane (meth) -25 acrylate changes by making it soluble in aqueous alkali, preserving the sensitivity of the compound to UV light. The carboxylation also improves adhesion to metals. Thus, the combination of a binder, a cross-linking agent and a carboxylated urethane di (and / or) tri (meth) acrylate provides an improved solder mask. A preferred combination will use a copolymer of styrene / maleic anhydride as a binder (which also provides carboxyl groups). Preferred crosslinking agents are the (meth) acrylate, and polyfunkial (meth) acrylate monomers.

Preferred carboxylated urethane di- (and / or) tri (meth) acrylates of the present invention can be represented by the formula shown in the formula 1 of the formula sheet where n is an integer p 'f' C & V

ψ · -βίε from 1-4; k can be either 0 or 1; and wherein R 1, derived from the acrylate reaction component (c), can be both a hydrogen atom and a methyl group; R 1 also obtained from the alkyl (meth) acrylate reaction component 5 (c), may be a linear or branched "saturated" hydrocarbon group having from 2 to 28 carbon atoms and is derived from the diisocyanate portion of the reaction mixture. or cyclic, saturated, unsaturated or aromatic hydrocarbon group. Rg may have from 4-20 carbon atoms and preferably from 6-18 carbon atoms. For other preferred embodiments, R 1 is derived from the diisocyanate reagent selected from trimethylhexamethylene, hexamethylene, isophorone, tolylene, 4,4-methylbis (cyclohexyl) methylenediphenyl, and tetramethyl-15-xylene diisocyanates. R ^ is a linear, cyclic or branched, aromatic, saturated or unsaturated hydrocarbon of from 2-28 carbon atoms. Optionally, R ^ may also contain a hydroxyl group (which remains from the polyol used in the preparation of the composition). R5 will be derived from a reaction mixture comprising (a) the carboxylic acid polyol shown and described for formula 2; or (b) the carboxylic acid polyol of formula 2 and from the hydroxyldicarboxylic acid shown in and described for formula 3. Thus, R 1 will always have at least one COOH group and a minimum number of 3 carbon atoms. When Rj. is derived from (a) (only from the compounds of formula 2) it will have only one COOH group and a branched or linear one; saturated, unsaturated or aromatic structure, preferably with a total of 3-30 carbon atoms including the carboxyl carbon atom. When R ,. is derived from (b), the total composition will have R 1 groups derived from the carboxylic acid polyol of formula 2 and also R 2 groups derived from the hydroxyldicarboxylic acids of formula 3. The R 3 groups derived of the hydroxyldicarboxylic acid compounds of formula 3, it will be appreciated, will have two COOH groups and may also have from 3-30 carbon atoms including the two carboxyl carbon atoms.

The description given here for the compounds

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t-7- of formula 2 and formula 3 will provide more information regarding the concentrations and preferred structures of these R1 groups.

It should be noted that the correct placement of each R 1 group in the polymer molecule will depend on the number of reactive hydroxyl groups of the compound of formula 2 or formula 3 and on the somewhat random condensation reaction. For example, when R ^ is derived from (b) and when y of formula 3 is one, R ^ will be an end group with two COOH groups; at the same time, other R groups of the same reaction mixture (obtained from the carboxylic acid polyol of formula 2) will be randomly placed in the base chain of the polymeric molecular structure as indicated above in formula 1.

In formula 1, R2 preferably has 2-16 carbon atoms, or more preferably, it is a group selected from the group consisting of ethyl, propyl, butyl formula 4 of the formula sheet wherein m = 1 or 2.

R1 is derived from the selected polyol which can be added to the reaction mixture. R 1 will therefore have 2-28 carbon atoms and 2-5 oxygen atoms.

The oxygen atoms may optionally be present in an unreacted hydroxyl group. When R 4 is present, it has from 2 to 28 carbon atoms, or preferably R 2 has from 2 to 16 carbon atoms; and optionally a hydroxyl group. Other preferred embodiments let R 1 be a saturated or unsaturated hydrocarbon group having from 2 to 10 carbon atoms and from 2 to 5 oxygen atoms, possibly as an unreacted hydroxyl group.

In specific examples of such preferred embodiments, R 4 is a group selected from: ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl, with 2 to 5 oxygen atoms of said hydroxyl groups.

4 may also be derived from glyceryl or 2-ethyl-1-2- (hydro-35-methylethyl) -1,3-propene.

The carboxylated urethane di- (and / or) tri (meth) acrylates of the present invention can be obtained by condensing a diisocyanate with a carboxylic acid polyol (see formula 2) and a hydroxyalkyl (meth) t / v L 1 : <2 * * -8- acrylate in a one-step reaction. The carboxyl-containing polyol can be any carboxylic acid containing 2 or more hydroxyl groups. Suitably there are 2 to 5 hydroxyl groups.

Preferably it is either carboxylic acid diol or triol.

Suitably, therefore, the carboxylic acid polyol may have the formula shown in formula 2 of the formula sheet wherein x is an integer of 2-5 and R is not a branched, cyclic or linear, saturated, unsaturated or aromatic hydrocarbon group having 2-29 carbon atoms. Preferably Rg has from 2 to 24 carbon atoms while x is 2 or 3 (as in a diol or triol). Most preferably x is 2 and Rg has a branched or linear; saturated, unsaturated, or aromatic, hydrocarbon structure of from 2 to 20 carbon atoms. A preferred embodiment uses an alpha-alpha-dimethylolalkanecarboxylic acid as a carboxylated diol, most preferably having an alkyl group of 1-8 carbon atoms. Other preferred diol carboxylic acids are selected from: alpha-alpha dimethylol acetic acid; alpha alpha dimethylol propionic acid, alpha alpha dimethylol butyric acid, alpha 20 alpha diethylol acetic acid; alpha alpha diethylol propionic acid, alpha alpha dipropylol propionic acid; alpha-alpha-dipropylol butyric acid, and 2,3-dihydroxypropanoic acid.

Optionally, a polyol can be added to the reaction mixture. This will increase the molecular weight of the present product. The presence of the polyol results in materials as shown under Formula 1 wherein k = 1.

Preferably, one embodiment of the present invention can be taken advantage of when a higher concentration of hydroxyl groups is present, (such as by adding a polyol or by using a carboxylic acid as shown in formula 2 wherein x is 3, 4 or 5) . In this embodiment, a hydroxyldicarboxylic acid is added to the reaction mixture. Formula 3 under 35 represents a formula of certain suitable hydroxylcarboxylic acids wherein y may be from 1 to 5 (preferably from 1 to 3) and R 1 is linear, cyclic, or branched; saturated, unsaturated or aromatic hydrocarbon group conveniently having 1-28 carbon atoms; preferably with from 1-18 f 7 Λ r / os * i £ V- 'ii »„ „-, · -fc-yg · - * (-9- and more preferably from 1-12 carbon atoms. When y is 2 to 5, it is preferably from 2-18 carbon atoms.

These diacids can preferably be used when the hydroxyl concentration of the total reaction mixture is at least about 0.3 milliequivalents of OH per gram of the combined amount of reactants (the diisocyanate, the carboxylic acid polyol, the Hydroxylalkyl (meth) acrylate, the hydroxyldicarboxylic acid and the polyol if present). These diacids can suitably be used in an amount of from about 0.3 to about 0.7 milliequivalents of acid per gram of the combined amount of reactants. Certain suitable hydroxydicarboxylic acids can be selected from the group consisting of malic acid, tartaric acid, dihydroxy tartaric acid, hydroxyadipic acid, dihydroxyadipic acid, and trihydroxyadipic acid.

These dicarboxylic acids can be used to provide thermally curable appendages or ends.

Advantageously, these ends can also provide reactive sites for future reactions with other materials.

For example, melamine and epoxy are two compounds or groups that can be reacted with the end carboxyl groups. Such reactions allow the properties of the material to be further modified or improved.

The desired specific properties or qualities will depend on the intended application of the material.

To prepare the present carboxylated urethane di- (and / or) tri (meth) acrylate coating composition, the reaction is carried out in a dry solvent solution which does not react with the isocyanate per se.

Suitable examples of such solvents are esters such as ethyl acetate and propylene glycol monomethyl ether acetate; ketones such as methyl ethyl ketone, methyl isobutyl ketone, and N-methyl pyrrolidone; aromatic hydrocarbons such as toluene, xylene; and mixtures of the above 35 substances.

The reaction to prepare the present coating composition is usually carried out with the solid content of the solution in the range of from about 20 to about 100% by weight, preferably in the .676 * 842- * «-10 range of about 35 to 95 wt%, and most preferably from about 65 to about 85 wt%. The reaction temperature is generally from about 50 to about 95 ° C, and preferably from about 65 to 85 ° C. Preferably, homopolymerization is inhibited by adding a free radical polymerization inhibitor such as hydroquinone, m-dinitrobenzene, phenothiazine, and the like. Most preferably they are used in an amount from about 0.005 to about 1% by weight based on the weight of solids.

In addition, it is preferable to use a condensation catalyst such as tin or amine catalysts. Such catalysts can be selected from the group consisting of: di-butyl tin dilaurate, dimethyl tin-15-dineodecanoate, dibutyltin bisoctyl thioglycolate, triethylamine, and triethylenediamine. For best results, the reaction is performed under a dry air blanket.

The diisocyanate can be a hydrocarbon that is branched, linear, or cyclic, saturated, unsaturated, or aromatic. Typically it has 4-20 carbon atoms, preferably it has 6-18 carbon atoms. Diisocyanates can be selected from the group consisting of: xylylene diisocyanate; 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane; 3,3'-dimethyldiphenylmethane-4,4'-25 diisocyanate; 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate; methylene bis (4-cyclohexyl isocyanate); hexamethylene diisocyanate; meta-tetramethylxylene diisocyanate; paratetramethylxylene diisocyanate; methylene bis-phenyl diisocyanate; 1,5-naphthylene diisocyanate; metaphenylene diisocyanate and mixtures of the above substances. Most preferred diisocyanates are: 2,6-tolylene diisocyanate; 2,4-tolylene diisocyanate; 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane; 2,2,4-trimethylhexamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

When a polyol is added, the molecular weight, cure speed, and crosslink density will increase. The polyol can be from 2-28 carbon atoms? <·; "- - ·. υ / w J -½ -

* P

-11- sitting. The hydrocarbon moiety can be branched or linear, saturated, unsaturated or aromatic and have from 2-5 hydroxyl groups. Preferably, the polyol is a diol or triol with 2-16 carbon atoms. Preferred diols can be selected from: ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, neopentyl glycol, 2-methylpropane-1,3-diol, cyclohexane dimethanol, and diethylene glycol. Other preferred polyols include glycerol, trimethylol propane, or hexanetriol which can also be used.

The hydroxyalkyl - (meth) acrylate (constituent C) may have an alkyl group having from about 2-28 carbon atoms. The alkyl moiety can also be linear cyclic or branched, saturated or unsaturated. Preferably, the alkyl group of the hydroxyalkyl (meth) acrylate has 2-12 carbon atoms. Certain preferred hydroxyalkyl (meth) acrylates can be selected from: hydroxyethyl (meth) acrylate, hydroxylpropyl (meth) acrylate, hydroxy-butyl (meth) acrylate, and compounds of the general formula 20 wherein m is one or two is.

When preparing the present coating composition, the concentrations of reactants should be such that the total concentration of hydroxyl groups is at least about equal to the amount of diisocyanate present. Generally, this means that the concentration of polyols plus diols of the dialkylol carboxylic acid plus the hydroxyalkyl (meth) acrylate is sufficient to bring the ratio of hydroxyl to diisocyanate at least about 0.95: 1, and preferably at least 30 1: 1 . Most preferably, the hydroxyl moiety has an excess of equivalents. Preferably, the hydroxyl should have an excess of equivalents relative to the diisocyanate in the range from about 1.05: 1 to about 0.95: 1; most preferred is in the range of from 1.02: 1 to about 1: 1.

The carboxylic acid polyol is an important component of the present coating composition and is preferably present in an amount sufficient to leave unhardened copolymer soluble or swellable. . - - -12- * * are in aqueous alkali solutions. Preferably, the carboxylic acid polyol is present in a minimum amount of about 0.3 milliequivalents of acid / gram of the total amount of reactants; preferably in an amount equal to or greater than 0.5 milliequivalents of acid / gram of the total amount of reactants.

The polar solubility is even higher when the carboxylic acid polyol is used in the reaction mixture in an amount greater than 0.8 of acid milli-equivalents per gram of the total amount of reactants (meq / g of TR).

A preferred range of acidic meq / g of TR is from about 0.8-1.6 acidic meq / g of TR. When a highly viscous product, which is extremely suitable for combining with other materials, is desired, it is preferred that the reaction mixture contain a minimum amount of about one acid meq / g of TR; a most preferred range is from about 1 to 1.6 acid meq / g of TR. The use of the divalent acid of formula 20 of the formula sheet can also be used to increase the amount of acid milliequivalents.

Another advantage provided by carboxylating urethane di- and tri (meth) acrylates is that the UV sensitive compound can be combined with water-loving resins. Furthermore, by varying the concentration of the carboxylation in the urethane di- and tri (meth) acrylates, the water-loving nature of this UV sensitive compound can be controlled to a certain extent. This makes it possible to set the water-loving character for a specific resin. Thus, if one wishes to use a more water-repellent or less water-loving resin, a low carboxylation concentration can be used in the urethane di- and tri (meth) acrylate to increase compatibility with the selected resin. In contrast, if one wishes to use a water-loving resin, the carboxyl group concentration would be increased such that the resin and urethane di- and tri (meth) acrylate can be mixed at higher concentrations. The carboxylic acid polyol can be used acceptably in the reaction mixture r "t V-"; s? s -13- in concentrations where the carboxylated polyol is present in an amount of from about 5 to about 45% by weight of the total amount of reactants (abbreviated as per part by weight TR), preferably from about 5 to about 25% by weight % TR, most preferably from about 12 to about 25% by weight TR.

When a particular polyol is also introduced, it can be used in the reaction mixture in an amount of from about 2 to about 18 weight percent TR; and 10 preferably with from 2 to about 15 weight percent TR.

For the diisocyanate, an acceptable concentration range is from about 30 to about 80 weight percent TR.

Preferably, this range ranges from about 50 to 75 wt% TR.

The hydroxyalkyl (meth) acrylate should be present in the reaction mixture in a minimum amount of about 0.50 meq acrylate / g of TR to ensure suitable UV sensitivity. A suitable range is from about 0.5 to about 1.6 meq acrylate / g of TR. An acceptable weight percent range ranges from about 5 to about 50% by weight of TR and preferably it is used in an amount from about 10 to about 30% by weight of TR.

The present carboxylated urethane di- (and / or) tri (meth) acrylate copolymer coating composition may acceptably have a weight average molecular weight of from about 500 to about 6500, preferably from about 800 to about 3000, and most preferably from about 1000 to about 2500 (determined by gel permeation chromatography and based on a standard polystyrene calibration curve).

In a preferred embodiment, the present coating composition is combined with a binder.

The preferred resin for this should have a glass transition temperature (Tg) of about 155 ° C or higher, and should preferably be water-loving. The high (Tg) will improve the temperature resistance. Several commercially available resins can be used. Compatible mixtures can • 870234? • * -14- are obtained with the present carboxylated urethane di- (and / or) tri (meth) acrylates, especially when suitably varying the carboxyl concentration. Acceptable resins that can be used for this purpose are styrene / maleic anhydride copolymers, especially those partially esterified with low molecular weight alcohols. Copolymers of styrene / maleic anhydride esterified with mixtures of alcohols from methyl to butyl are commercially available. Such copolymers are commercially available in a wide molecular weight range. Typically, the molecular weight of this resin binder will range from about 25000 to about 300000; and more preferably from about 60000 to about 250000. Preferably, the copolymer used has a styrene to maleic anhydride ratio in the range of about 1: 1 to about 2: 1. A preferred (Tg) range for the binder is from about 155 ° C to about 200 ° C.

Typically, the binder can be used in an amount of from about 85% to about 25% by weight of the total composition, and preferably from about 17% to about 60% by weight of the total composition. Preferably, the carboxylated urethane di ((and / or) tri (meth) acrylate) coating composition is mixed with the binder such that the glass transition temperature (Tg) of a final product is from about 70 to about 190 ° C. Preferably, the binder acid number is from about 120 to about 280 mg KOH / g of the binder. Other polymers of the above molecular weight, Tg, 30 and acid number can also be used as a binder with the present carboxylated urethane di (and / or) tri (meth) acrylate coating composition. Suitable polymers for use as binders include: methyl methacrylate comethacrylic acid and methyl methacrylate methyl 35 acrylate methyl acrylic acid.

When the present carboxylated urethane di- (and / or) tri (meth) acrylate is used with other materials such as the above-described binders, or other additives that may be added, 8702942

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Such as cross-linking agents, dyes, solvent pigments, photoinitiators, thermal inhibitors, the concentration of the UV sensitive carboxylated coating component should be in the range of about 10 to about 85% by weight of the total combined composition. Preferably it is in the range from about 15 to about 75 wt%, and most preferably in the range from about 17 to about 60 wt% of the total combined composition.

Preferred cross-linking agents are the (meth) acrylate monomers. Cross-linking agents are used when it is desirable to obtain a composition with a higher cross-linking density, which in turn improves resistance to solvents such as methylene chloride.

More preferred are polyfunctional (meth) acrylate monomers. Such polyfunctional monomers can be selected from: trimethylolpropane tri (meth) acrylate, trimethylpropane ethoxylated tri (meth) acrylate, dipentaerythritol hydroxypentaacrylate, and ditrimethylolpro-20 tetraacrylate.

Other cross-linking agents that can be used can be selected from the group consisting of divinyl ethers, acrylated epoxides, epoxy resins, and aminoplastic resins. The acrylated epoxides are preferred as they improve overall heat resistance, solvent resistance adhesion, and total improvement.

When the present carboxylated coating composition is used as a solder mask, the composition is layered onto a suitable substrate and dried to tack-free state. The coated substrate is imaged at approximately 2 75-105 mJ / cm. UV radiation, and can then be developed with an aqueous alkaline solution. Preferably, the aqueous alkali solution is potassium or sodium carbonate. Generally, the exposed coated substrate is currently under review.

When using the present coating composition, it is advantageous that, if desired, a coating can be easily removed with an aqueous alkaline cleaner and re-treated. The amount of alkali required in the stripping agent or developing solution is very small. A solution containing 1% by weight of the base can be used. When the desired quality of an image is obtained, the present coating can be given a post-UV curing of 3-5 J / cm. This is followed by heat curing preferably at 150 ° C for a sufficiently long curing time. The present compositions have particularly good resolution properties, flexibility and adhesion to metals.

The present invention can also be easily understood from the following examples. It should be understood, however, that these examples are given to illustrate the present invention and should not be used to limit the invention. All parts and percentages are by weight unless otherwise indicated.

Example 1 ♦ The following example illustrates a preparation of the photosensitive coating composition.

The following ingredients were placed in a 5 liter round bottom flask equipped with a mechanical stirrer, a thermometer, a condenser, a gas inlet 25 and a heating jacket: 236.0 g (g), (about 4 equivalents), of 1.6 hexanediol ; 268.0 g (about 4 equivalents) of dimethylol propionic acid; 951.2 g (about 8.2 equivalents) of 2-hydroxyethyl acrylate; 0.23515 phenothiazine as a free radical inhibitor; 783.8 g of N-methyl-2-pyrroli-30 don as a solvent; and 31.35 g (dibutyltin dilaurate (T-12) as a catalyst. Under dry air and stirring, 1,680.0 g (about 16 equivalents) of trimethylhexamethylene diisocyanate was introduced into the mixture in two equal portions at 30 minute intervals. An exothermic reaction took place with each addition 35. The reaction temperature was kept below 85 ° C by cooling with an ice water bath and after the second addition of trimethylhexamethylene diisocyanate, the reaction temperature was kept at a constant value of 85 ° C for 10-12 hours until the O '7 AA = -:>. V {V t-t * 17 -isocyanate infrared absorption peak disappeared, indicating that the reaction was complete.

Example 2.

The photosensitive coating layer composition prepared in Example 1 was used to prepare a photosensitive solder mask. The solder mask was prepared by introducing the following ingredients into a 500 ml round bottom flask run with stirrer, gas inlet, thermometer 10 and condenser: 6.5 g of a low molecular weight copolymer defoamer; 91.25 g of N-methyl-2-pyrrolidone as a solvent; to which 82.0 g of an esterified styrene / maleic anhydride copolymer was added as a binder. (The resin used here was Scripset 550, Monsanto).

The mixture was stirred and heated to 95 ° C for 30 min to obtain a cloudy solution. After this, the temperature was lowered to 70 ° C, after which the following ingredients were added to the mixture: 0.004 g of the free radical polymerization inhibitor, phenothiazine; 77.5 g of the UV sensitive coating composition prepared according to example 1, and 9.0 g of a green pigment. While the mixture was kept under a stream of dry air, a pre-mixed solution containing the following substances was added: 47.8 g of trimethylolpropane triacrylate (SR351) as a cross-linking agent, 6.5 g of isopropylthioxanthone (abbreviated as ITX) as photoinitiator and 8.4 g of ethyl p-dimethylaminobenzoate (abbreviated to EPD) as sensitizer.

The above ingredients were mixed under dry air for 30 min at 70 ° C, after which the mixture was placed in an amber bottle. The solder mask thus prepared was used as described in Example 3.

35 Example 3.

The composition prepared in Example 2 was applied as a coating to two 15 x 20 cm uncovered copper-coated epoxy backings in a thickness of about 50 µm using a 75 mesh monofilament 0 7 * V / v Ah. V '

* V

Polyester sieve and a rubber squeegee with a durometer hardness of 70. This wet coating was dried to a coat of tack-free 35 µm in an oven with forced air circulation at 100 ° C over a period of 12 min.

After these dried thin layers were cooled to room temperature, they were exposed to 75 mj / cm. by an IPC (Institute for Interconnecting Packaging electronic circuits) No. B-25 negative design with a 400 watt mercury vapor lamp. The light-exposed thin layers were then manually developed in a 1% solution of 10 CO 2 for 45 sec. and then rinsed with tap water.

An excellent resolution of the IPC B-25 was obtained.

After this development, the plates were cured with

2 Q

3 J / cin and baked at an elevated temperature at 150 ° C for 1 hour as post-curing.

One of the substrate plates was then soaked in methylene chloride (abbreviated MeCl 2) for 15 min.

And no deterioration of the mask was observed (solvent resistance test).

The other plate underwent a cross-cut adhesion test according to ASTM D3359-78 Method B, and no adhesion losses were found. The plate was then coated with a resin flux, allowed to float on a molten solder pot at 260-275 ° C for 10 min with the solder mask side underneath.

After the solder pot test, the plate was immediately washed clean with 1,1,1-trichloroethane while the plate was still warm. An hour later, the plate underwent the same cross cut adhesion test and no loss of adhesion was observed.

Example 4.

Using the device and the general method as described in Example 1, urethane diacrylate oligomers were prepared which varied in the degree of carboxylation. Sample 4 had no carboxylation and Sample 9 had the highest degree of carboxylation. Each £ r-_ e \ n,? The samples were prepared on the basis of 80% solids. The composition of each individual sample used is shown in Table 1 below.

Table 1 ♦ 5 The following abbreviations have been applied.

DMPA = dimethylolpropionic acid 2HEA = 2-hydroxyethyl acrylate TMDI = trimethylhexamethylene diisocyanate DTN = dimethyltindineodecanoate 10 M-Pyrol = N-methylpyrrolidone eq. = equivalent.

Monster 4 Monster 5 eg. weight eq. weight (g) Cg) 15 1.6 hexanediol 8 472 7.0 413.0 DMPA - - 1.0 67.0 2HEA 8.1 939.6 8.2 951.2 TMDI 16 1680.0 16.0 1680 .0 DTN - 15.46 - 15.56 20 M-pyrol - 772.9 - 777.8

Phenothiazine - 0.309-0.311

Sample 6 Sample 6 eq. Weight eq. Weight (g) (g) 25 1.6 Hexanediol 3.0 177.0 2.0 118.0 DMPA 5.0 335.0 6.0 402.0 2HEA 8.2 951.2 8.2 951.2 TMDI 16.0 1680.0 16.0 1680.0 DTN - 15.72 - 15.76 30 M-Pyrol - 785.8 - 762.8

Phenothiazine - 0.314 - 0.315

Monster 8 Monster 9 eq. Weight eq. Weight (g) (g) 35 1.6 Hexanediol 1.0 59.0 0 0 DMPA 7.0 469.0 8.0 536.0 2HEA 8.2 951.2 8.2 951.8 TMDI 16.0 1680.0 16.0 1680.0 DTN - 15.8 - 31.67 6- 'rt - τ * -20- M-Pyrol - 789.8 - 791.8

Phenonthiazine - 0.316 - 0.317

The viscosity facts of samples 4 to 9 were measured (in CPS) at 24 ° C using a Brookfield 5 RVT viscometer, $ 6 spindle at 10 rpm.

Sample Φ 4 5 6 7 8 9 viscosity 20 400 22 400 41 600 44 800 68 800 86 400.

Example 5.

Samples 5-9 of the carboxylated urethane acrylates were used to prepare solder masks. These solder masks were then tested for comparison of properties. This example, together with Examples 6 and 7 that follow, can be used to compare the properties of the carboxylated urethane acrylates of masks containing the non-carboxylated urethane acrylates.

The solder masks, indicated below as Example D-H, were prepared using equipment 20 and general procedure as described in Example 2.

The amount of each constituent is indicated in the following table:

Table 2.

A common solder mask composition 25 for samples D-H.

Modaflow (a low molecular weight copolymer) 6.5 N-methylpyrrolidone 91.25

Styrene / maleic anhydride (Scripset 550) 82.0

Phenothiazine 0.004 Carboxylated urethane acrylate 77.5

Green pigment (9G5) 9.0

Isopropylthioxanthone 6.5

Ethyl p-dimethylaminobenzoate 8.4

Trimethylolpropayl triacrylate (SR351) 47.8 35 Summary of properties of solder masks with carboxylation.

Solder Mask (Sample No.) D E F G H

Carboxylated ur ethane 5 6 7 8 9

Using the solder masks of samples, ε / c 2 s -21- «? D-H, bare copper-coated epoxy plates were coated in the usual manner as described in Example 3. The plates were then tested and evaluated, 2

Exposure speed - was particularly good at 75 mJ / cm 5 for sample D-H.

Development; For samples D-H in a 1% aqueous I 2 CO 2 solution was particularly good.

Evolution in 1,1,1-trichloroethane for sample D-H was poor.

10 Adhesion Testing Method; ASTM-D3359-78 method B (scale 5 = No adhesion loss) (scale O = Complete adhesion loss)

Sample number D E F G H

Adhesion before melted 15 solder 5 4-5 4-5 5 4-5

Adhesion after that molten solder wax was applied 55555

Example 6.

Samples of a solder mask composition, using Sample 4 with the uncarboxylated material, were prepared as described in Example 2 as follows.

Ingredients and amounts of the components are shown in the following table:

Table 3

Solder mask Solder mask

Sample composition A Sample B

(Defoamer) 1r10 1.30 30 N-methylpyrrolidone 41.8 50.35

Scrip set 550 30.68 36.50

Phenothiazine 0.0024 0.003

Green pigment (9G5) 3.1 3.1

Sample 4 29.0 75.0 35 SR351 16.2

Isopropylthioxanthone 2.25 3.0 EPD 3.1 4.0

To provide a comparison using a method as described in Example 3. 8 7 I-1 '-: ·:

* V

t-22- each of these compositions (A and B) was tested and used to coat a bare copper clad epoxy sheet as indicated. The results are shown below.

Solder mask Solder mask

Monster A Monster B

Limited Tolerable - Total Phase Separation

Stability at 24 ° C 1 month --- 10

Development 1% aqueous excellent --- 1,1,1-trichloroethane poor ---

Property

Methylene chloride resistance was poor due to showing the action of the solvent after only 2 minutes exposure.

The adhesion before the molten solder * 5 after the molten solder * 5 SR351 = Trimethylolpropane triacrylate 20

ITX = Isopropylthioxanthone EPD = Ethyl p-dimethylaminobenzoate * Cross Cut Adhesion- ASTM-D3359-7B Method B

Scale 5 = no adhesion loss

Scale 5 = total adhesion loss.

25

Example 7.

Also for comparison purposes, Sample 4 material was used to produce a photosensitive element which was then evaluated for development in different types of solvents. The photosensitive element (Sample C) was prepared by mixing the ingredients in Table 3 at 50 ° C in a 500 ml round bottom flask equipped with a stirrer, a gas inlet, a thermometer and a condenser.

The table below indicates the amount of each component.

8702842% S-23 Table 3.

Containing a solder mask composition (sample C)

Non-carboxylated urethane diacrylate (Sample 4) 5 Composition (g)

Sample 4 urethane diacrylate 122.5

Elvacite 2008 94.0 PMA 131.0

Phenothiazine 0.0044 10 Irgacure 651 6.2

Leuco Crystal Violet (dye) 0.2

Development.

in 1,1,1-trichloroethane excellent in 1% aqueous ï ^ CO ^ none 15 Abbreviations used above:

Elvacite 2008 = polymethyl methacrylate (MW = 79000) PMA = propylene glycol monomethyl ether acetate Irgacure 651 = 2,2-dimethoxy-2-phenylacetophenone

The non-carboxylated urethane diacrylate (sample 20 star 4) had very limited compatibility with the styrene / maleic anhydride resin (Scripset 550). Homogeneous mixtures of the non-carboxylated urethane diacrylate and the styrene / maleic anhydride resin could only be obtained for a relatively short period of time (less than 1 month); but only if the urethane diacrylate resin ratio was less than one. When the ratio increased, phase separation occurred (sample B).

However, the carboxylated urethane di- or tri (meth) acrylate may have different carboxylation concentrations, allowing them to be mixed and combined in all proportions with the styrene / maleic anhydride resin and other binder resins. The results are exceptional in terms of longevity, uniformity and good properties of the 35 products.

Example 8,

Carboxylated urethane triacrylate samples were prepared using the apparatus and the general procedure described in Example 1. The specific ingredient. 8702§42 w Jr-24- part and for each triacrylate sample are given in the table below.

Table 5.

Sample 10 Sample 11 5 (eq.) (Wt. In g) (eq.) Wt. G) 1.6 hexanediol 2.0 118.0 --- ---

Tone 0301 ---- --- 4.0 400.0

Glycerol DMPA 2.0 61.4 --- --- DMPA 4.0 268.0 4.0 268.0 10 2HEA 8.1 939.6 --- ---

Tone M-100 --- --- 8.2 2820.8 TMDI 16.0 1680.0 --- --- IPDI --- --- 16.0 1777.6 DTN --- --- - - 52.66 15 T-12 --- 30.67 M-Pyrol --- 766.8 1316.6

Phenothiazine --- 0.23 --- 0.395

Abbreviations used in table:

Tone 0301 = polycaprolactone triol with molecular weight 20 300.

Tone M-100 = a reactive caprolactone acrylate.

IPDI = isophorone diisocyanate = 1-isocyanato-3-isocyanato-methyl-3,5,5-trimethylcyclohexane.

The product from samples 10 and 11 was then used to make solder masks of resp. prepare samples I and J.

The solder masks were prepared using the equipment and the general procedure described in Example 2.

Table 6

Solder mask compositions based on carboxylated urethane triacrylates. Composition Monster I Monster J

35 Modaflow 1.10 1.10 N-methy1 41.8 41.8

Scripset 550 30.68 30.68

Phenothiazine 0.0024 0.0024 (Sample 10) 29.0 --- Ê * 7 Λ η λ g n '{V: 4, b' H £.

-25- (sample 11) --- 29/0

Green pigment 9G5 3rl 3.1 ITX 2.25 2.25 EPD 3/10 3.10 5 SR351 16.2 16.2

Developmental features; in 1 wt% aqueous particularly good particularly good

MeCl2 resistance 6 min (good) 8 min (good) (Tested by dipping 10 in the solvent for the specified time period and judging the results as good if no effect is seen, bad if a solvent action is seen).

Cross Cut Adhesion Test - ASTM-D3359-78 Method B

Scale 5 = no bonding loss 15 Scale O = total bonding loss

Adhesion before melted solder 5 4 after melted solder 5 3

The plates used in the above experiments were prepared using samples I and J 20 according to the procedure described in example 3.

8 * f ft λ <*

Claims (13)

1. A photosensitive coating composition, characterized in that it comprises: an ultraviolet radiation-sensitive polymer selected from the group consisting of: a carboxylated urethane dimethacrylate, a carboxylated urethane diacrylate, a carboxylated urethane triacrylate, and a carboxylated urethane tri methacrylate; wherein said UV sensitive polymer is formed by condensing a reaction mixture consisting of component (a): a diisocyanate of 6-18 carbon atoms, component (b): a carboxylic acid polyol of the formula sheet; wherein x may be an integer from 2-5, and wherein 15 is a linear or branched, saturated, unsaturated or aromatic, hydrocarbon group having from 2-29 carbon atoms, and component (c) is a hydroxyalkyl (meth) acrylate, the alkyl group of which of 2-28 carbon atoms; provided that component (a) is present in an amount from about 30 to about 80% by weight of the total amount of the reaction mixture; component (b) is present in an amount of from about 5 to about 45% by weight of the total amount of the reaction mixture with a minimum of about 0.3 milliequivalents of acid per gram of the total amount of reaction mixture, and component (c ) is present in an amount of from about 5 to about 50% by weight of the total amount of reaction mixture with a minimum amount of 0.5 milliequivalents of acrylate per gram of the total amount of the reaction mixture. 2. A composition according to claim 1, characterized in that it also contains a binder. 3. A composition according to claim 1, characterized in that the reaction mixture also contains a polyol having from 2 to 28 carbon atoms and from 2 to 5 hydroxyl groups. Composition according to one or more of claims 1 to 3, characterized in that the reaction mixture also comprises a dicarboxylic acid of the formula, 87 0 2 i. 2 5 '-27-3 of the formula sheet wherein y is an integer from 1 to 5 and wherein is a hydrocarbon moiety with 1 to 28 carbon atoms. Composition according to one or more of claims 1 to 4, characterized in that component (b) is further selected from the group consisting of: alpha-alpha-dimethylol-acetic acid, alpha-alpha-dimethylolpro- pionic acid, alpha-alpha-dimethylolbutyric acid, alpha-alpha-diethanol acetic acid, alpha-alpha-diethylol propionic acid and alpha-10 alpha-diethylol butyric acid. Composition according to one or more of claims 3-5, characterized in that the binder is a styrene / maleic anhydride copolymer with a glass transition temperature of about 155 ° C or higher. Composition according to one or more of claims 1 to 6, characterized in that the reaction mixture contains about 0.8-1.6 milliequivalents of acid per gram of the total amount of the reaction mixture. Composition according to one or more of claims 1 to 7, characterized in that the diisocyanate is selected from the group consisting of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane; xylene diisocyanate; 3,3'-dimethyldiphenylmethane-4,4'-di-25 isocyanate; 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; 2,2,4-trimethylhexamethylene diisocyanate; 2,4,4-trimethylhexamethylene diisocyanate; methylene bis (4-cyclohexyl diisocyanate); hexamethylene diisocyanate; 1,5-naphthylene-diisocyanate; metaphenylene diisocyanate; metatetramethyl-30-xylene diisocyanate; paratetramethylxylene diisocyanate; and methylene bisphenyl diisocyanate. 9. A composition according to claim 8, characterized in that it also contains a cross-linking agent. A process for the preparation of a polymer sensitive to UV radiation, characterized in that it comprises conducting a condensation reaction with a reaction mixture comprising: component ia): a diisocyanate with 6-18 carbon-8 "7 A / ti 'ϋ L ·. r * * * (-28- atoms, and component (b) a carboxylic acid polyol of the formula 2 wherein x can be an integer from 2-5, and wherein R is a linear or branched, O saturated, unsaturated or an aromatic hydrocarbon-5 group having from 2-29 carbon atoms, and component (c) is a hydroxyalkyl (meth) acrylate whose alkyl group has from 2-28 carbon atoms, provided that component (a) is present in an amount of about 30 up to about 80% by weight of the total amount of the reaction mixture; component (b) is present in an amount of from about 5 to about 45% by weight of the total amount of the reaction mixture with a minimum of about 0.3 milliequivalents of acid per gram of the total amount of reaction mixture, and component (c) is present in an amount of about 5 to about 50% by weight of the total amount of reaction mixture with a minimum amount of 0.5 milliequivalents acrylic per gram of the t total amount of the reaction mixture. Process according to claim 10, characterized in that the temperature of the reaction mixture is in the range of about 50 to 95 ° C. 12. Process according to one or more of claims 10-11, characterized in that the reaction mixture also comprises a free-radical polymerization inhibitor and a condensation catalyst. Process according to any of claims 10-12, characterized in that the reaction mixture is kept under dry air during the reaction. 30 -------- s 7 f o ^ »Ö t i · X- l.