Esacure ONE by IGM Resins is a difunctional oligomeric alpha hydroxy ketone. It is a type I photoinitiator. Provides through and surface cure. Formula (1) was prepared using both Esacure M (A) and Esacure ONE (B). The results of the tests performed are reported in figures 1 & 2. Curing was. ONE offers very low odor levels and low migration but suffers from low solubility. A liquid version, Esacure ONE 75, is a 75% solution of ONE in 25% ethozylated.
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Kind code of ref document: Ref legal event code: Country of ref document: Year of fee payment: The present invention relates to a homogenous liquid blend comprising a photoinitiator and an alkoxylate surfactant for incorporation into aqueous based and solvent based radiation curable systems. A potential problem is that many photoinitiators are solid at room temperature and have to be dissolved before incorporating them into coating formulations.
Solubilizing solid photoinitiators into the coating formulation may require excess oone additional diluents that esacjre adversely affect the properties of the coating or may be undesirable from environmental aspects. Moreover, the use of solid photoinitiators often results in processing disadvantages during manufacture of UV-curable paints. They often require longer times of oen until a uniform distribution and dissolution has been achieved. In addition, especially with waterborne UV-curable paints, it is also very difficult to control the status of homogeneous dissolution as the paint formulation is esacuree itself turbid.
These problems lead to higher processing effort and less reproducible quality. Therefore liquid photoinitiators esacuee preferred for producing of UV-curable paints. Other options include dissolving the photoinitiators in the reactive diluent, dissolving a solid photoinitiator in a liquid one, and dissolving the photoinitiators in nontoxic, nonvolatile solvents that do not adversely affect coating properties. These mixtures are liquid within a certain mixing range, and can therefore be quickly incorporated in a simple manner into liquid or pasty compositions.
This solution is not suitable for aqueous systems. A dispersing agent is dissolved in water and the photoinitiator is added at room temperature. The suspension obtained is then treated in a colloid mill to obtain particles in the range of 0.
The European Patent EP Lamberti discloses an aqueous dispersion comprising a photoinitiator and a surfactant. The surfactant is e. At first a homogeneous solution is prepared by esacurf the photoinitiator at elevated temperatures to the surfactant.
To the homogeneous solution water is added. The solution thus cools down and solidifies. A dispersion esacurre particles of the photoinitiator is obtained.
The dispersion is grinded. As an aqueous dispersion there still remain disadvantages in that the photoinitiator particles may settle on prolonged storage and that the aqueous dispersion is incompatible to many non-aqueous UV-systems. Higher concentrations of the photoinitiator are not disclosed.
ESACURE ONE by LEHVOSS Group – Paint & Coatings
The problem underlying the present invention is to provide a liquid photoinitiator blend which remains liquid and homogeneous i. Said blend should be suitable for aqueous based and solvent based radiation curable systems. It has now been found that mixing a photoinitiator of the radical type with a liquid surface active agent, and optionally with an organic diluent leads to a homogenous liquid blend with a high content of photoinitiator and which is stable at room temperature.
Compared to the dispersed photoinitiator of EP Lamberti which is a heterogeneous system the present invention is a homogeneous system at room temperature.
Lamberti requires water esacurr obtain a heterogeneous product form at room temperature. Also high energy input is required to ome the product form dispersing process. The term “homogenous liquid blend” generally describes a substance in a liquid phase, without the presence of a secondary droplet esaure particle phase that could separate. The liquid blend has at room temperature a viscosity not higher than mPas and therefore can be processed as a liquid with standard technical equipment for pumping and mixing of liquid materials.
The alkoxylated surface active agent is responsible for the emulsifying properties and for esacire compatibility of the resulting photoinitiator additive concentrate towards aqueous and non-aqueous formulations like paint or ink formulations. Preferably, the pure surfactant is a liquid at room temperature.
The term “alkoxylated liquid surface active agent” refers to compounds in which one or more straight or branched C 1 -C 22 alkyl chains are connected through the residue of a linking group to an oligomeric or polymeric chain of alkylene oxide residues. The lne also refers to compounds in which one or more aromatic groups, which can be alkylated, are connected through the residue of a linking group to an oligomeric or polymeric chain of alkylene kne residues.
The term also refers to compounds containing one or more acetylenic groups, which can be connected through the residue of a linking group to one or two oligomeric or polymeric chains of alkylene oxide residues. The term also refers to block-copolymers or random copolymers of ethylene oxide and propylene oxide. The linking group can be an oxygen atom hydroxyl group residue from alcohol or phenol ; a carboxyl group fatty acid or ester residue ; an amino group amine group residue ; or a carboxyamido carboxylic amide residue.
The surface active agent is thus selected from alcohol alkoxylates glycol ethersfatty acid alkoxylates, fatty amine alkoxylates, or fatty amide alkoxylates, alkoxylates of phenols or alkylsubstituted phenols, block copolymers or random copolymers of ethylene oxide and propylene oxide, alkoxylates of alkine-alcohols or alkine-diols, alkoxylates of castor oil, alkoxylates ohe sorbitan fatty acid esters and mixtures thereof.
Examples of suitable alkoxylated surface active agents include:. The C 1 -C 22 alkyl group in the above mentioned alkoxylates esacire linear or branched, saturated or unsaturated and preferably C 6 -C Examples of suitable alkoxylated liquid surface active agents include also compounds in which a straight or branched C 1 -C 22 alkyl chain is connected through the residue of a linking group onee defined above to multifunctional alcohols like trimethylolpropane, sugar derivatives like sorbitan esters, triglycerides like castor oil and the like.
Preferred are non-ionic surfactants having a poly onw oxide group, such as a poly- ethylene oxide group or a poly propylene oxide group or mixtures thereof. Examples are compounds sold under the Trade Mark Brij such as polyoxyethylene 4 lauryl ether Brij 30 or polyoxyethylene 20 cetyl ether Brij 58polyoxyethylene 20 stearyl ether Brij 78 and polyoxyethylene 20 oleyl ether Brij 92 or polyethylene glycol monomethyl ether MPEG.
Also preferred are non-ionic surfactants derived from ethoxylated esters of fatty acids with rsacure or sorbitan, such as polyoxyethylene glycerine monostearate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan-monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan trioleate.
The sorbitan esters fsacure sold under the tradename Tween, like polyoxyethylene 20 sorbitan monolaurate Tween 20polyoxyethylene 20 sorbitan monopalmitate Tween 40polyoxyethylene 20 sorbitan monostearate Tween 60ssacure 20 sorbitan tristearate Oe 65polyoxyethylene 20 sorbitan monooleate Tween 80polyoxyethylene 20 sorbitan trioleate Tween Examples of suitable alkoxylated fatty acids are: Examples of block copolymers of ethylenoxide and propylene ssacure are the products sold under the Pluronics trademark like: Examples of alkoxylates of alkine-alcohols or alkine-diols are product sold under the Trademarks: Also preferred are non-ionic surfactants derived from ethoxylates of vegetable oils or animal fats, such as corn oil ethoxylate, castor oil ethoxylate, tallow oil ethoxylate.
An example for a castor oil ethoxylates is one marked under the trademark Hedipin. The surfactant can be a blend of all classes of alkoxylated surface active substances described previously. Optionally one or more organic diluents may be present. The optional onw diluent provides additional stability of the photoinitiator concentrate and assists in improving compatibility of the photoinitiator concentrate towards different end use formulations.
Benzene, (1-methylethenyl)-, homopolymer, ar-(2-hydroxy-2-methyl-1-oxopropyl) derivs.
The optional organic diluent is chosen from the group consisting of high boiling inert liquids based on ester and or ether compounds like: Also suitable are high boiling liquid alcohols like C10 to Calcohols or polyols. Examples of oligoethylene glycols include: Examples of organic diluents based on ester fluids include: Examples of ether fluids are diethylene glycol dibutyl ether and phenoxyethanol Examples of alcohols are isodecanol, CC15 oxoalcohols, propylene glycol, dipropylene glycol, tripropylene glycol, oligoethylene glycols like diethylene glycol, triethylene glycol, tetraethylene glycol and glycerin.
In one embodiment the organic diluent is present.
Optionally the blend may contain water. Small amounts of water may not have a negative impact concerning the stability of the inventive photoinitiator blends as well as concerning the compatibility of the inventive photoinitiator blends for non-aqueous systems.
The inventive homogeneous liquid esadure is obtainable by a process comprising the steps of.
The inventive free flowing liquid is suitable for aqueous and solvent based systems. Higher active contents essacure obtainable as compared to previous solutions like the waterborne dispersions of photoinitiators described in EP Lamberti and EPB1 Ciba and in GB Minesota Mining In addition the inventive homogenous liquid blends show better storage stability, especially at elevated temperatures, as there are no heterogeneous photoinitiator particles which may irreversibly esacuer like in the case of noe dispersion.
The invention further relates to a photopolymerizable composition comprising. The unsaturated compounds may include one or more olefinic double bonds. They may be of low monomeric or high oligomeric molecular mass.
Examples of monomers containing a double bond are alkyl or hydroxyalkyl acrylates or methacrylates, for example methyl, ethyl, butyl, 2-ethylhexyl or 2-hydroxyethyl acrylate, isobornyl acrylate, methyl methacrylate or ethyl methacrylate.
Interesting also are resins which are modified with silicon or fluor, e.
Other examples are acrylonitrile, acrylamide, methacrylamide, N-substituted meth acrylamides, vinyl esters such as vinyl acetate, vinyl ethers such as isobutyl vinyl ether, styrene, alkyl- and halostyrenes, N-vinylpyrrolidone, vinyl chloride or vinylidene chloride.
Examples of monomers containing two or more double bonds are the diacrylates of ethylene glycol, propylene glycol, neopentyl glycol, hexamethylene glycol or of bisphenol A, and 4,4′-bis 2-acryl-oyloxyethoxy diphenylpropane, trimethylolpropane triacrylate, pentaerythritol triacrylate or tetraacrylate, vinyl acrylate, divinylbenzene, divinyl succinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate or tris 2-acryloylethyl isocyanurate.
Examples of polyunsaturated compounds of relatively high molecular mass oligomers are acrylated epoxy resins, acrylated polyesters, polyesters containing vinyl ether or epoxy groups, and also acrylated polyurethanes and polyethers. Further examples of unsaturated oligomers are unsaturated polyester resins, which are usually prepared from maleic acid, phthalic acid and one or more diols and have molecular weights of from about to In addition it is also possible to employ vinyl ether monomers and oligomers, and also maleate-terminated oligomers with polyester, polyurethane, polyether, polyvinyl ether and epoxy main chains.
Particularly suitable examples ine esters of ethylenically unsaturated carboxylic acids and polyols or polyepoxides, and polymers having ethylenically unsaturated groups in the chain or in side groups, for example unsaturated polyesters, polyamides and polyurethanes and copolymers thereof, alkyd resins, kne and butadiene copolymers, polyisoprene and isoprene copolymers, polymers and copolymers containing meth acrylic ezacure in side chains, and also mixtures of one or more such polymers.
Examples of unsaturated carboxylic acids are acrylic acid, methacrylic acid, crotonic acid, itaconic acid, cinnamic acid, and unsaturated fatty acids such eaacure linolenic acid or oleic acid.
Acrylic and methacrylic acid are preferred. Suitable polyols are aromatic and, in particular, aliphatic and cycloaliphatic polyols. Examples of aromatic polyols are hydroquinone, 4,4′-dihydroxydiphenyl, 2,2-di 4-hydroxyphenyl propane, and also novolaks and resols. Examples of polyepoxides are onee based on the abovementioned polyols, especially the aromatic polyols, and epichlorohydrin.
Other suitable polyols are polymers and copolymers containing hydroxyl groups in the polymer chain or in side groups, examples being polyvinyl esacuure and copolymers thereof or polyhydroxyalkyl methacrylates or copolymers thereof. Further polyols which are suitable are oligoesters having hydroxyl end groups. The polyols may be partially or completely esterified with one carboxylic acid or with different esacuge carboxylic acids, and in partial esters the free hydroxyl groups may be modified, for example etherified or esterified with other carboxylic acids.
The homogeneous liquid blend as defined above is used to produce solvent-free, solvent- or water-based surface coatings, printing inks, screen-printing inks, offset-printing inks, flexographic-printing inks, resist materials or image-recording material, especially in the production of corresponding aqueous systems. Liquid photoinitiator product forms of the following photoinitiators were prepared: The mixture is cooled slowly to room temperature.
The product form is a clear, colorless to yellow liquid. The product form is a clear yellowish liquid. The product form is a clear, colorless to onee viscous liquid. In the following the photoinitiator refers to its onee liquid blend delivery form, not to the active content.
A UV-curable paint is prepared using the following formulation: The extend of curing was followed by measurement of acrylate noe bond conversion DBC against the resin itself as reference using AT-IR spectroscopy of the coating surface.
The acrylate peak at approx. In addition pendulum hardness according to Koenig was measured on all panels. A further advantage is shown for the aqueous systems.