Abstract: A deposition system has a multi-material print head, a first reservoir of a first compatible material having particles containing chemical elements similar to a first substrate, a second reservoir of a second compatible material having particles containing chemical elements similar to a second substrate, a third reservoir of an polymer precursor material, and at least one mixer. A method of bonding a joint between dissimilar substrate materials includes functionalizing a first compatible material having chemical elements similar to a first substrate, mixing the first compatible material with a polymer precursor material, functionalizing a second compatible material having chemical elements similar to a second substrate, mixing the second compatible material with a polymer precursor material, and using the deposition system to deposit the first and second compatible materials and a polymer precursor material on the joint between the first and second substrate materials.

Abstract: The invention relates to a fatty acid diamide-based rheology additive composition, which is pre-activated and pre-concentrated in fatty acid diamide, comprising: a) from 5% to 30% by weight of at least one fatty acid diamide based on 12 hydroxystearic acid and on a linear, in particular C5, C6 or C7, aliphatic diamine, b) from 70% to 95% by weight of at least one monofunctional (meth)acrylic reactive diluent comprising a cycloaliphatic group or several cycloaliphatic groups, the % being expressed relative to a)+b). It also relates to a process for preparing the composition and to the use thereof as a rheology additive in reactive binder compositions such as coating, moulding, composite material, anchor bolt or sealant compositions or photocrosslinkable compositions for stereolithography or for 3D printing of objects by inkjet.

Abstract: Provided are an actinic-radiation-curable resin composition that has high storage stability and that combines high levels of ease of application and adhesion to various substrates and high levels of coating appearance and heat resistance after curing, an actinic-radiation-curable primer for metallization that contains such an actinic-radiation-curable resin composition, and a shaped article including an undercoat layer for metallization that has good adhesion to various substrates. Specifically, an actinic-radiation-curable resin composition is provided that contains an oil-modified alkyd resin and a (meth)acryloyl-containing compound. The oil-modified alkyd resin is prepared using two or more oils having iodine values of 100 or more and has an oil length of 30 to 60, a mass average molecular weight of 200,000 to 1,000,000, and a molecular weight distribution (Mw/Mn) of 50 or more.

Abstract: The present invention relates to a radiation curable composition comprising at least one (meth)acrylated compound compound (A); and at least one inert polyester (B) that is prepared from a (i) polyol component comprising at least one cyclic ether polyol and (ii) from a polyacid component. The present invention further relates to their preparation and uses.

Abstract: A UV-curable composition for coating vehicle axles includes at least one aliphatic epoxy acrylate and at least one acrylate selected from the group consisting of aromatic epoxy acrylate and polyester acrylate as a photochemically crosslinkable component; at least one reactive diluent; at least one photoinitiator; and at least one filler and/or at least one pigment.

Abstract: Photoinitiators mixture comprising (i) at least one compound selected from the group consisting of alpha-hydroxy ketones, monoacylphosphine oxides, bisacylphosphine oxides, ketosulfones, benzil ketals, benzoin ether, phenylglyoxylates, borates and titanocenes; and (ii) at least one compound of the formula (I) or (I?) R1, R?1, R2 and R2? R?9 independently of each other for example are hydrogen or C1-C12alkyl R7, R8, R9, R?8 and R?9 independently of each other for example are hydrogen, C1-C12alkyl which optionally is substituted or phenyl which optionally is substituted, exhibit excellent photoinitiating properties.

Abstract: A sealant that can be used in a liquid crystal display device without contaminating the liquid crystal layer is presented. The sealant includes an acrylic-based compound having at least two acryl groups per molecule and an epoxy-based compound having an epoxy group and a dihydrazide compound. A liquid crystal display using the sealant is provided. The liquid crystal display includes a first substrate having a display area, a second substrate on the first substrate and a liquid crystal layer interposed between the first and second substrates. A sealant pattern is formed on any one of the first and second substrates in an outer portion of the display area by using the sealant.

Abstract: Compounds of the formula I or (I?), wherein R1 and R?1 for example are hydrogen, C3-C8cycloalkyl or C1-C12alkyl, R2 and R2? for example are hydrogen; unsubstituted C1-C20alkyl or substituted C1-C20alkyl; and R8 and R9 for example are hydrogen, C1-C12alkyl which optionally is substituted, or phenyl which optionally is substituted; exhibit an unexpectedly good performance in photopolymerization reactions.

Abstract: Disclosed is a photosensitive resin composition for a color filter protective layer including a cross-linkable alkali soluble resin including a repeating unit represented by the following Chemical Formula 1, a reactive unsaturated compound, a photopolymerization initiator, and a solvent. In Chemical Formulae 1 to 3, R1 to R6 and A1 to A3 are the same as in the detailed description.

Abstract: The present invention relates to a polymer resin compound including a new polycyclic compound, and a photosensitive resin composition including the polymer resin compound as an effective binder matrix. In particular, the photosensitive resin composition according to the present invention uses a polymer resin compound, which includes a compound having double cyclic structure in one molecule as a monomer, as a binder matrix. Accordingly, the photosensitive resin composition has an excellent photosensitivity and an excellent developing property, and has a low distortion property during plastic processing. For this reason, the photosensitive resin composition has an advantage of curing various transparent photosensitive materials used to manufacture a color filter of a liquid crystal display, for example, a column spacer, an overcoat, a passivation material, and the like.

Abstract: The present invention relates to a photochromic composition comprising multifunctional (meth)acrylate-based monomers having two or more functional groups, a photochromic dye and an aromatic vinyl compound, in which the content of the aromatic vinyl compound is more than 30% by weight and 70% by weight or less, a photochromic film produced by using the same, and a method for producing the photochromic film.

Abstract: Disclosed is a photosensitive resin composition including (A) a photopolymerizable monomer including a compound represented by the following Chemical Formula 1, wherein the substituents of Chemical Formula 1 are the same as defined in the specification, (B) a binder resin, (C) a photopolymerization initiator, (D) a pigment and (E) a solvent, and a color filter using the same.

Abstract: A colored curable composition including: (A) a pigment dispersion containing (a-1) a pigment, (a-2) a compound having a pigment mother nucleus structure and an amino group in a molecule, and (a-3) a resin having an acid group and a polymerizable group; (B) an oxime ester initiator; and (C) a polymerizable compound.

Abstract: Disclosed are a photosensitive resin composition for a color filter and a color filter including the same. The photosensitive resin composition for a color filter may include (A) an acrylic-based copolymer including a structural unit represented by the following Chemical Formula 1 and a structural unit represented by the following Chemical Formula 2, wherein the substituents of Chemical Formula 1 and Chemical Formula 2 are the same as defined in the specification; (B) an acrylic-based photopolymerizable monomer; (C) a photopolymerization initiator; (D) a pigment; and (E) a solvent.

Abstract: Disclosed are a photosensitive resin composition and a light blocking layer using the same. The photosensitive resin composition includes (A) a cardo-based monomer represented by the following Chemical Formula 1 or 2, wherein the substituents of Chemical Formula 1 and Chemical Formula 2 are the same as defined in the detailed description, (B) a cardo-based resin, (C) a reactive unsaturated compound, (D) a pigment, (E) an initiator, and (F) a solvent.

Abstract: Disclosed are a photosensitive resin composition for a color filter and a color filter using the same. The photosensitive resin composition for a color filter may include (A) a copolymer including a structural unit represented by the following Chemical Formula 1, wherein the substituents of Chemical Formula 1 are the same as defined in the specification; (B) an acrylic-based photopolymerizable monomer; (C) a photopolymerization initiator; (D) a pigment; and (E) a solvent.

Abstract: Disclosed is a photocurable resin composition for additive fabrication comprising a polymerizable component that is polymerizable by free-radical polymerization, cat ionic polymerization, or both free-radical polymerization and cationic polymerization, and a photoinitiating system capable of initiating the free-radical polymerization, cationic polymerization, or both free-radical polymerization and cationic polymerization. The photocurable resin composition is a liquid at about 25° C., and is capable of curing to provide a solid upon irradiation with light emitted from a light emitting diode (LED), wherein the light has a wavelength of from about 100 nm to about 900 nm. Also disclosed is a three-dimensional article prepared from the photocurable resin composition for additive fabrication, and a process for preparing three-dimensional articles by additive fabrication.

Abstract: Disclosed are a photosensitive resin composition for a color filter and a color filter using the same. The photosensitive resin composition for a color filter includes (A) an acrylic-based binder resin including a structural unit represented by the following Chemical Formula 1, wherein the substituents of Chemical Formula 1 are the same as defined in the specification; (B) an acrylic-based photopolymerizable monomer; (C) a photopolymerization initiator; (D) a pigment; and (E) a solvent.

Abstract: Disclosed are a photosensitive resin composition that includes (A) a cardo-based resin including repeating units represented by the following Chemical Formulae 1 and 2, wherein the substituents of Chemical Formulae 1 and 2 are the same as defined in the specification, (B) reactive unsaturated compound, (C) a pigment, (D) an initiator, and (E) a solvent, and a light blocking layer using the photosensitive resin composition.

Abstract: The present invention relates to a photosensitive resin composition for a color filter and a color filter fabricated using the same. The photosensitive resin composition includes (a) an acrylic-based resin, (b) a photopolymerizable monomer, (c) a photopolymerization initiator, (d) a pigment, and (e) a solvent. The acrylic-based resin is a copolymer including a repeating unit of an ethylenic unsaturated monomer including a carboxyl group and a repeating unit of an ethylenic unsaturated monomer including an alkoxy 4-oxo butanoic acid group. The photosensitive resin composition for a color filter can have residue removing characteristics, and is capable of forming fine pixels and providing a color filter having high resolution.

Abstract: Provided are a photosensitive resin and a photosensitive resin composition comprising the photosensitive resin. The photosensitive resin has the structure of Formula 1, which is described in the specification. The photosensitive resin and the photosensitive resin composition have good sensitivity, improved resistance to heat and chemicals, and excellent storage stability. Further provided are a method for preparing the photosensitive resin and a cured product of the photosensitive resin composition.

Abstract: Radiation curable compositions comprising at least one radiation curable oligomer obtained from the reaction of one or more carboxyl functional polyester (a) having a glass transition temperature TG and/or melting temperature Tm of less than 30° C., with (b1) one or more (meth)acrylated mono-epoxide, and/or (b2) one or more polyepoxide and one or more ?, ? unsaturated carboxylic acid.

Abstract: The present invention provides a polymerizable composition, comprising, based on the total weight of the polymerizable composition: (a) 1-90 wt % of a monomer of a formula (I): wherein X1 is H or methyl; X2 is H or C1-C2 alkyl; X is O or S; R1 is C1-C12 straight or branched alkylene or alkoxylene; and d and n are each independently an integer of 0 to 3; and (b) 0.1-10 wt % of a photo-initiator. The present invention also provides an optical film comprising a coating formed from the above polymerizable composition. The optical film can be used in backlight units for displays as a brightness enhancement film.

Abstract: A photosensitive resin composition which is excellent in flame resistance, resolution and flexibility, and substantially free from deposition of components thereof to prevent contamination of a product. The photosensitive resin composition comprises: (A) a cyclic phosphazene compound represented by the following general formula (1): wherein at least one of the Rs is an organic group having the urethane(meth)acrylate structure represented by the following general formula (2) and n is a positive number of 2 to 5: wherein R1 is a hydrogen atom or a methyl group; (B) a carboxyl-containing linear polymer obtained by polymerizing an ethylenically unsaturated compound through addition polymerization; (C) an epoxy resin; (D) an ethylenically unsaturated group-containing polymerizable compound; and (E) a photopolymerization initiator; wherein the cyclic phosphazene compound (A) is present in a proportion of 5 to 30 wt % based on the total weight of the composition.

Abstract: The invention features dental compositions comprising at least one hybrid monomer that comprises a cyclic allylic sulfide moiety attached to a (meth)acryloyl moiety. These two functional moieties are typically joined either directly to each via a chemical bond or through some chemical structure or spacer molecule. The composition may optionally contain additional polymerizable compounds, such as ethylenically unsaturated compounds, that are typically used in dental compositions.

Abstract: A radiation curable powder coating composition for preparing low gloss coatings, comprises as a binder a mixture of 30 to 90 weight % of one or more (meth)acryloyl group containing amorphous polyester resins having an unsaturated equivalent weight of more than 700 g/double bond and an isophthalic acid content of from 65 to 100 weight %, calculated on all the acids, and 10 to 70 weight % of one or more (meth)acryloyl group containing acrylic copolymers having an unsaturated equivalent weight of up to 1250 g/double bond.

Abstract: A radiation curable powder coating composition for preparing low gloss coatings, comprises as a binder a mixture of 30 to 90 weight % of one or more (meth)acryloyl group containing amorphous polyester resins having an unsaturated equivalent weight of more than 700 g/double bond and 10 to 70 weight % of one or more (meth)acryloyl group containing acrylic copolymers having an unsaturated equivalent weight of less than 700 g/double bond.

Abstract: Ink deposited on a substrate by an ink-jet arrangement to form a protective layer includes hardenable oligomer, hardenable monomer selected from a group including alkoxylated and/or poly-alkoxylated acrylic monomers comprising one or more di- or tri-acrylates, and a photoinitiator. The oligomer has a room temperature viscosity greater than 1 Pa·s. The oligomer to monomer weight ratio is between 1/6 and 1/25. The ink has a room temperature viscosity between 15 and 22 mPa·s and between 5 and 2 mPa·s at 60° C., and a room temperature surface tension between 15 and 28 mN/m. The photoinitiator is activated by a UV source having an appropriate wavelength and intensity.

Abstract: A 3D-inkjet printing method includes the steps of a) providing two or more fluids having a different composition to an inkjet printer; b) mixing the two or more fluids in a controlled amount; c) jetting the mixture of the two or more fluids with the inkjet printer onto a support; d) at least partially curing the jetted mixture by actinic radiation or electron beam; and e) repeating steps b) to d) in order to build a 3D-relief on the support. The method is capable of printing 3D-objects with inkjet fluid sets in an inkjet printer.

Abstract: Aqueous radiation curable binders comprising non-ionically stabilized epoxy resins ABC. Resins ABC are an adduct mixture of: adducts formed by the reaction of polyethylene glycol-modified epoxy resins A with olefinically unsaturated acids C, and adducts formed by the reaction of epoxy resins B, that are free from polyethylene glycol derived groups, with olefinically unsaturated acids C. A process for preparing aqueous radiation curable binders comprising non-ionically stabilized epoxy resins ABC, and a process of coating a substrate with aqueous radiation curable binders comprising non-ionically stabilized epoxy resins ABC.

Abstract: A radiation curable composition comprising a (meth)acrylated polyester having unsaturated (meth)acrylic groups on the molecules, responding to formula (I) or formula (II) wherein each D, independently, represents ethylene or propylene, x, y is an integer from (1) to (50), each A, independently, represent hydrogen, alkyl, alkenyl, with the proviso that adjacent A's can be linked together to form a cycle, each B, independently, represents an alkylene or alkenylene chain, optionally comprising one or more ether bridges, each R, independently, represents hydrogen or methyl.

Abstract: Disclosed are radiation-curable, abrasion resistant coating compositions for thermoplastic substrates which provides superior abrasion, chemical, and impact resistance properties. The coating composition includes at least one flexible diacrylate component, at least one aromatic diacrylate component, and at least one urethane acrylate. Also disclosed are shaped articles having the coating composition applied to at least one surface and cured by exposure to radiation.

Abstract: Compounds of formula (I): {where n is a number from 1 to 6; R3 is hydrogen, methyl or ethyl; A represents a group of formula —[O(CHR2CHR1)a]y—,—[O(CH2)bCO]y—, or —[O(CH2)bCO]y—,—[O(CHR2CHR1)a]-(where one of R1 and R2 is hydrogen and the other is hydrogen, methyl or ethyl); a is from 1 to 2; b is from 4 to 5; y is from 3 to 10, Q is a residue of a polyhydroxy compound having 2 to 6 hydroxy groups; and x is greater than 1 but no greater than the number of available hydroxyl groups in Q} and esters thereof are useful as photoinitiators for the preparation of energy-curable compositions, such as printing inks

Abstract: Disclosed are radiation curable putty compositions that include (a) a radiation curable material, (b) a radiation cure initiator, and (c) a filler comprising a polymer, such as a polymer that is transparent to ultraviolet radiation. Also disclosed are methods for refinishing a coated substrate utilizing such putty compositions, and articles coated with such putty compositions.

Abstract: Zero VOC compositions are described and may include: one of vinyl ester solids, unsaturated polyester solids (e.g., isophthalic polyester, orthophthalic polyester, terephthalic polyester, and mixtures thereof), and mixtures thereof; polymerizable solids (e.g., a monomer, an oligomer, and mixtures thereof); and/or at least one photochemical catalyst. Zero VOC compositions may be produced by: heating polymerizable solids to a range of about 300° F. to about 500° F.; and adding one of vinyl ester solids, unsaturated polyester solids, and mixtures thereof. Additional steps may include reducing the heat to about 70° F. to about 100° F. and adding at least one photochemical catalyst and/or at least one additive. Zero VOC compositions may be curable without requiring evaporation of a VOC there from upon exposure to ultraviolet light and/or mixing with at least one thermal catalyst.

Abstract: An energy curable lithographic ink composition having an asymptotic relative viscosity of about 0.4 to about 1.5 and a water up-take number of at least about 30%. Also disclosed is a method of improving various rheological properties and increasing the water window of an energy curable lithographic ink by varying the composition of the ink in order to result in an asymptotic relative viscosity of about 0.4 to about 1.5 and a water up-take number of at least about 30%. A method of identifying and selecting an energy curable lithographic ink composition having optimal press performance is also disclosed.

Abstract: A photocurable and thermosetting resin composition comprising (A) a photosensitive prepolymer having a carboxyl group in combination with at least two ethylenically unsaturated double bonds in its molecule, (B) a polymerization initiator, (C) a diluent, (D) an oxetane compound having at least two oxetanyl groups in its molecule, and (E) a curing promotor is developable with an alkaline solution and can be formulated as a one package preparation. Such a photocurable and thermosetting resin composition and a photosensitive dry film prepared by the use thereof are useful as various resist materials and electrical insulating materials, particularly as solder resists for printed circuit boards, interlaminar insulating materials for build-up multi-layer printed circuit boards, and the like.

Abstract: A photo curable resin composition, which comprises (A) an acid-modified, vinyl group-containing epoxy resin, (B) an elastomer, (C) a photopolymerization initiator, (D) a diluent and (E) a curing agent, can give a high performance cured film having distinguished heat resistance, humidity-heat resistance, adhesibility, mechanical characteristics and electrical characteristics, and a photosensitive element, which comprises a support and a layer of the photo curable resin composition laid on the support, has distinguished heat resistance, humidity-heat resistance, adhesibility, mechanical characteristics and electrical characteristics.

Abstract: A polymerizable compound represented by formula (1): wherein each R1 independently represents at least one organic residue selected from the group consisting of alkylene groups, branched alkylene groups, cycloalkylene groups and arylene groups, R2 represents an organic residue derived from an alcohol compound, a phenol compound or a carboxylic acid compound, n represents an integer of 0 to 20, a production process of the polymerizable composition, a composition using the polymerizable compound, a cured product obtained by curing the composition and a production process of the cured product. The polymerizable compound exhibits a good adhesive property to a substrate such as glass and is imparted with radical polymerizability to enable heat curing and/or active energy ray curing.

Abstract: A solvent-containing multicomponent system curable thermally and with actinic radiation (dual cure) and comprising (A) at least one component comprising (A1) at least one constituent containing at least 1.8 meq/g of isocyanate-reactive functional groups, (A2) at least one constituent containing at least 1.8 meq/g of isocyanate-reactive functional groups and at least one functional group having at least one bond which can be activated with actinic radiation, and (B) at least one component comprising at least one polyisocyanate (B1); and its use as a coating material, adhesive or sealing compound.

Abstract: A high refractive index, curable, synthetic resin composition comprising a core resin composition composed of a mixture of ethylenically unsaturated compounds, and an initiation system containing both photo and thermal initiators, particularly a photochromic resin composition which further includes at least one photochromic dye. Also a curing process, which includes a combination of multi-step radiation curing and thermal annealing. Articles produced of cured composition exhibit superior physical and, in appropriate cases, photochromic properties and can be easily mass produced on a commercial scale due to short processing time and use of readily available chemicals.

Abstract: Aqueous storage-stable, non-sedimenting photoinitiator suspensions comprising (a) a mono- or bis-acylphosphine oxide of formula (I), wherein R1 is C1-C20alkyl; C2-C20alkyl interrupted by one or more O atoms; C1-C12alkoxy; phenyl-C1-C4alkyl; or phenyl that is unsubstituted or substituted by C1C20alkyl, C1-C12alkoxy, halogen, cyclopentyl, cyclohexyl, C2-C12alkenyl, C2-C18alkyl interrupted by one or more O atoms, and/or by phenyl-C1-C4alkyl; or R1 is biphenylyl; R2 is an aromatic radical or has one of the meanings give for R1; R3 and R4 are each independently of the other C1-C12alkyl, C1-C12alkoxy or halogen; and R5 is hydrogen, C1-C12alkyl, C1-C12alkoxy or halogen; (b) a dispersant; and (c) water are suitable especially in the photopolymerisation of aqueous formulations comprising ethylenically unsaturated monomers.

Abstract: This invention relates to a photo- or heat-curable resin composition which yields a cured product with minimal cracking and high reliability. The resin composition of this invention comprises 100 parts by weight of (A) photo- or heat-polymerizable unsaturated compound composed of a polycarboxylic acid adduct of bisphenol-epoxy (meth)acrylate, 10-100 parts by weight of (B) alkylene oxide-modified product of (meth)acrylate or oligomers thereof, 0-50 parts by weight of (C) compound containing epoxy group and 0-50 parts by weight of (D) photopolymerization initiator or sensitizer. The composition exhibits high heat resistance and good microfabrication quality and is useful as a peripheral material of electronic parts such as semiconductor devices by the build-up process, for example, as a material for forming insulation layers in multilayer printed wiring boards.

Abstract: Liquid composition polymerizable, by means of radicalic polymerization, into organic glass, comprising the product obtained from the transesterification of a mixture of diallyl carbonate (A) and a phthalic ester (B), with one or more polyols (C), linear or branced, containing from two to eight carbon atoms in the molecule.

Abstract: An adhesive/sealant which is curable by radiation exposure composition having at least one of adhesive and sealant properties and comprising a radiation polymerizable vinyl material, a polymerization initiator for radiation polymerization of the vinyl material, a thermosetting epoxy-containing material and a heat-activatable hardener for the epoxy-containing material.

Abstract: The invention relates to a binder, preferably for coating materials, which is curable thermally and/or by high-energy radiation and comprises a mixture of substances comprising (a) as one component, monomers or polymers which have a least one vinyl ether, vinyl ester, (meth)acrylic and/or allyl group and (b) as a further component, saturated polymers and/or unsaturated polymers different from component (a), with the proviso that at least one of components (a) and (b) has structural units of the formulae (I) and/or (II) the other component (b) has structural units of the formulae (I) and/or (II) at least when it contains saturated polymers. The invention also relates to a process for preparing the binder and to a formulation which comprises the binder of the invention. This formulation is in the form of a pigmented or unpigmented coating material or powder coating material.

Abstract: Dental composites containing hybrid fillers and process for their production. Dental compounds are disclosed which contain two- or multi-phase inorganic fillers in an organic polymer matrix. These are characterized by improved abrasion resistance.

Abstract: A photo curable resin composition, which comprises (A) an acid-modified, vinyl group-containing epoxy resin, (B) an elastomer, (C) a photopolymerization initiator, (D) a diluent and (E) a curing agent, can gives a high performance cured film having distinguished heat resistance, humidity-heat resistance, adhesibility, mechanical characteristics and electrical characteristics, and a photosensitive element, which comprises a support and a layer of the photo curable resin composition laid on the support, has distinguished heat resistance, humidity-heat resistance, adhesibility, mechanical characteristics and electrical characteristics.

Abstract: A composition for coating an optical waveguide, more specifically, an optical fiber, and optical fibers coated therewith. The coating composition is a radiation curable composition including an aliphatic epoxide, a urethane acrylate oligomer, a reactive diluent, and cationic and free-radical photoinitiators. The cationic photoinitiator acts upon the aliphatic epoxide while the free-radial photoinitiator acts upon the urethane acrylate oligomer. The resulting cured coating forms an interpenetrated polymer network. The properties of coatings in accordance with the invention including the glass transition temperature thereof, can be tailored to achieve advantageous coatings suitable for use as primary coatings and secondary coatings for an optical fiber.

Abstract: An improved photoimagable cationically polymerizable epoxy based solder mask is provided that contains a non-brominated epoxy resin system and from about 0.1 to about 15 parts, by weight per 100 parts of resin system, of a cationic photoinitiator. The non-brominated epoxy-resin system has solids that are comprised of from about 10% to about 80% by weight, of a polyol resin having epoxy functionality; from about 0% to about 90% by weight of a polyepoxy resin; and from about 25% to about 85% by weight of a difunctional epoxy resin. The photosensitive cationically polymerizable epoxy based system is especially useful as a solder mask and does not contain bromine.