HK1130323A - Cationic composition and methods of making and using the same - Google Patents

Description

Cationic compositions and methods of making and using the same

Technical Field

The present invention relates to cationic compositions and methods of making and using these compositions in stereolithography applications. In a preferred embodiment, the present invention relates to iodonium-based cationically curable compositions comprising antioxidants and methods that help reduce potential runaway reactions (runaway reactions) when these compositions are exposed to actinic radiation in large quantities.

Background

Cationically polymerizable iodonium-based formulations are known in the art. Various means have been taught to enhance the storage stability of such formulations using specific stabilizers, however, the art does not address how to reduce run away reactions when iodonium-based cationic polymerizable compositions are exposed to actinic radiation in large quantities.

U.S. patent No. 5,973,020 describes a mixture of tolylene tetrakis (pentafluorophenyl) borate tolylene iodonium(s) and diacetone containing an amino agent (amino agent) stabilizer. It is proposed that such mixtures may provide improved storage stability.

WO 2005/070989a2 teaches the use of organophosphorus stabilizers and sterically hindered nitroxyl stabilizers in cationic polymerizable formulations to improve storage stability.

U.S. Pat. No. 6,649,259B 1 discloses cationic polymerizable iodonium based epoxy (resin) compositions comprising hindered phenolic antioxidants. The composition is used as an adhesive layer on a heat-shrinkable polymer film.

U.S. Pat. No. 6,967,224B 1 and U.S. Pat. No. 6,685,869B 1 disclose a photocurable resin composition suitable for three-dimensional photofabrication, which comprises (a) a cationic polymerizable organic compound, (B) a cationic photoinitiator, and (C) a (co) polymer obtainable by (co) polymerization of monomers including at least one monomer containing a (meth) acrylate group. A method for producing a three-dimensional product (object) comprises using a detergent having a hansen solubility between 27-35(Mpa) sup.1/2.

While previously disclosed stabilizers can be used to improve shelf-life (shelf-life) stability, such stabilizers often have sufficient alkalinity to reduce cure speed in cure-sensitive cationic applications, as well as limit continuous dark-reaction cationic cure in applications such as stereolithography.

Disclosure of Invention

The present invention relates to cationically polymerizable iodonium based compositions comprising phenolic, phosphite and/or lactone antioxidants which are substantially neutral to slightly acidic. The addition of the phenolic, phosphite and/or lactone antioxidants is effective to reduce run-away polymerization induced by exposure of the formulation to actinic radiation in bulk. The addition of the phenolic, phosphite and/or lactone antioxidants reduces cure degradation upon imagewise actinic exposure as well as dark reaction cure degradation upon completion of actinic exposure.

The invention may be embodied as a composition comprising:

a) a cationic polymerizable compound;

b) an iodonium-based cationic initiator;

c) a photosensitizer for the cationic initiator; and

d) an antioxidant selected from the group consisting of phenolic antioxidants, phosphite antioxidants, lactone antioxidants, and combinations thereof; wherein the amount of antioxidant is between 0.01 and 10 wt% with respect to the total weight of the composition.

In another embodiment of the present invention, the antioxidant is selected from the group consisting of phenolic antioxidants, lactone antioxidants, and combinations thereof.

In another embodiment of the invention, the antioxidant is a phenolic antioxidant and the amount of the phenolic antioxidant is between 0.01 and 2 wt%.

In another embodiment of the invention, the antioxidant is a phosphite antioxidant and the amount of phosphite antioxidant is between 0.01 and 2 wt%.

In another embodiment of the invention, the antioxidant is a lactone based antioxidant and the amount of the lactone based antioxidant is between 0.01 wt% and 2 wt%.

In another embodiment of the invention, the antioxidant is a phenolic antioxidant and the amount of the phenolic antioxidant is between 0.02 wt% and 0.1 wt%.

In another embodiment of the invention, the antioxidant is a phosphite antioxidant and the amount of phosphite antioxidant is between 0.1 wt% and 1 wt%.

In another embodiment of the invention, the antioxidant is a lactone based antioxidant and the amount of the lactone based antioxidant is between 0.02 wt% and 0.1 wt%.

The cationic polymerizable compound used in the present invention preferably contains at least one compound containing an epoxy group such as glycidoxy, alicyclic epoxy, etc., and/or a compound containing an oxetane group.

The composition of the present invention may also be a mixed composition and thus may include, in addition to the cationic polymerizable compound, a radical type polymerizable compound such as a compound containing one or more (meth) acrylate groups.

Another embodiment of the invention is a method of making a three-dimensional article comprising forming a mold from the composition of the invention and forming a thermoplastic sheet on the mold by a vacuum forming technique.

In another aspect, the invention is embodied in a mold (mold) or pattern (pattern) formed from the composition of the invention.

In yet another aspect, the invention is embodied in a method of forming a cationically cured material comprising subjecting a cationically curable composition to cationic curing conditions for a time sufficient to form a cured material therefrom. A preferred embodiment of the present invention is a method of forming a three-dimensional article by means of photocuring stereolithography (stereolithography ), by (a) coating a layer of a cationically curable composition as described herein on a surface; (b) imagewise exposing the layer to actinic radiation to form an imaged cross-section, wherein the radiation provides sufficient exposure to substantially cure the layer in the exposed areas; (c) applying a layer of the composition over the previously exposed imaged cross-section; (d) exposing the layer from step (c) to imagewise actinic radiation to form an additional imaged cross-section, wherein the radiation is of sufficient intensity to substantially cure the layer in the exposed areas and to cause it to adhere to the previously exposed imaged cross-section; and (e) repeating steps (c) and (d) a sufficient number of times to form a three-dimensional article. The article may be a mold or pattern, for example, a Quick-Cast pattern used in investment casting.

The present invention provides a method of forming a cationically cured material comprising subjecting a cationically curable composition to cationic curing conditions for a time sufficient to form a cured material therefrom.

The present invention further provides a process for making a stereolithography pattern comprising a) preparing an iodonium-based cationically curable composition, and b) exposing said composition to actinic radiation.

The present invention also provides a method for reducing the potential for runaway polymerization (potential) in a process comprising the steps of:

a) providing a plurality of iodonium-based compositions; and

b) exposing the composition to actinic radiation,

wherein the composition comprises an antioxidant selected from the group consisting of phenolic antioxidants, phosphite antioxidants, lactone antioxidants, and combinations thereof.

The invention can be used in processes where the exposure is an imagewise exposure or a flood exposure. Such a method is, for example, a stereolithography method or a printing plate method. The addition of phenolic, phosphite and lactone antioxidants to cationically polymerizable iodonium based formulations is particularly useful in applications such as stereolithography where the formulation is imagewise exposed in a manner that initiates cationic cure but does not immediately result in complete cure. The compositions of the present invention are useful for reducing the tendency of runaway reactions when they are exposed to actinic radiation in large quantities.

Detailed Description

Certain terms are used herein to define certain chemicals and concepts:

"bulk exposure" refers to actinic exposure of a formulation applied to a thickness of 0.4cm or greater when applied to a surface or when contained in a container (or vat), such as in stereolithography, having a container depth typically greater than a few centimeters.

"flood exposure" refers to exposure of the surface of a photopolymer to actinic radiation wherein the amount of actinically exposed surface at any one time is 50% or more of the total photopolymer surface available for exposure. For example, if the exposure of the photopolymer surface is through a mask, wherein the mask transmits or reflects greater than 50% of the actinic light such that it exposes greater than 50% of the photopolymer surface at a time, then this will be a flood exposure. However, if the exposure is done, for example, with a scanning laser beam over the surface of the photopolymer, such exposure will be "imagewise exposure". Even if the laser scanning imagewise exposure provides greater than 50% exposure to the photopolymer surface, it does not achieve full exposure at the same time, but the exposure will occur in one area and then another over time. Such exposure would be imagewise exposure if the mask blocked 50% or more of the light from the surface of the photopolymer. Thus, if sunlight irradiates more than 50% of the photopolymer surface at any time, the stereolithography container (where the photopolymer surface is not protected from light) is placed in a daylight window to create a flood exposure.

"phenolic antioxidants" comprise in their structure a phenol ring, a naphthol ring, a phenanthrol ring and/or an anthracenol ring.

"lactone antioxidants" comprise in their structure a phenoxy ring, a naphthoxy ring, a phenanthryloxy ring, and/or an anthracyloxy ring.

"phosphite antioxidants" comprise in their structure a phenoxy ring, a naphthoxy ring, a phenanthryloxy ring and/or an anthracyloxy ring, as well as aliphatic phosphites.

In the development of cationically polymerizable compositions for stereolithography, laboratory procedures were: preparation of small-scale formulations of experimental compositions; pouring the composition into a polystyrene petri dish; various experiments were performed on the compositions; the petri dish was then placed in an actinic light post-curing device to harden (cure) the composition by flood exposure. While the above-described laboratory operations are essentially safe when handling non-iodonium-based cationically polymerizable compositions (e.g., sulfonium-based compositions), the above-described operations, when used with iodonium-based compositions, can result in run-away polymerization reactions including smoking, splashing, and potential burning.

Cationic polymerizable formulations that typically include iodonium cationic initiators are used in situations where the thickness of the coated formulation is relatively thin prior to exposure. In thin coatings, there is little chance of a runaway exothermic polymerization reaction, since the heat generated during curing is readily absorbed by the environment, such as the atmosphere or the coated substrate. Problems arise in the case of formulations which are largely exposed to actinic light in one piece and in which heat from the exothermic reaction (exotherm) can build up in the composition where polymerization and latent polymerization occurs. The case of bulk exposure, particularly where actinic radiation can be absorbed from many directions, such as flood exposure, can lead to the problem of uncontrolled exothermic polymerization that the present invention seeks to eliminate.

The tendency of iodonium-based cationic polymerizable compositions to exhibit such runaway reactions when exposed to actinic radiation in large quantities leads to safety issues during use of such compositions by customers as well as during shipping. For example, if a container is dropped during shipment of a composition based on an iodonium initiator chemical, the composition may leak and pool on pavement or airport asphalt materials, while on sunny days, uncontrolled polymerization induced by actinic exposure from the sun may shut down highways or may cause closure of airports. Or if the stereolithography user is to remove a vat of iodonium-based cationic polymerizable resin from the stereolithography machine and place it in front of a window that is being exposed to sunlight in an uncovered manner. The barrel of resin may cause combustion or expose personnel to hazardous fumes from the burning of the resin if a photo-induced runaway reaction occurs.

The above potential and other circumstances have led to a need to try to stabilize iodonium-based cationically polymerizable compositions in order to minimize the possibility of runaway reactions, while not significantly compromising the performance of the composition during imagewise actinic exposure or during substantially dark reactions following cationic curing.

Alternatively, another commercial use of iodonium-based compositions is the production of models by means of stereolithography, for example for investment casting. It is well known in the art of stereolithography that molds, such as the "Quick-Cast" mold, can be prepared by stereolithography. The Quick-Cast model has an outer skin that matches the perimeter of the part to be molded and also has an internal stent-type structure. The cradle-type structure may ensure proper structural integrity of the skin while allowing uncured resin to drain from the mold skin. After the Quick-Cast mold is prepared by means of stereolithography, the interior uncured resin may be drained from the mold, and the mold may then be immersed in various ceramic slurry baths to form a pre-ceramic shell around the mold. The pattern with the surrounding pre-ceramic shell is then heated and fired in various steps to harden the pre-ceramic into a ceramic investment casting mold. During this process, the pattern is burned off, forming a ceramic investment casting mold.

Currently, there is a concern in the industry about stereolithography molds containing antimony, among which the following problems sometimes exist: the antimony is not completely burned off, leaving a certain amount of antimony still present in the ceramic mold. When the molten metal is then poured into the ceramic shell, the residual antimony interacts with the metal, producing a metal part with surface defects or producing regions of metal alloy in the part with undesirable physical properties (e.g., cracking tendency or lower melting point). Such problems are more pronounced with superalloy components, for example, with cast turbines for turbine engines. For such uses, iodonium-based cationic initiators that do not contain antimony are preferred. However, when a model such as Quick-Cast is prepared using an iodonium-based cationic curable composition, sometimes the region of the Quick-Cast model is not completely emptied. If the Quick-Cast model is post-cured in a PCA (post cure device), and if it contains a large amount of unexpelled composition, there is a possibility of a runaway reaction.

Various methods for reducing the likelihood of such runaway reactions were investigated. Hindered amines, weak bases such as polyvinylpyrrolidone, amphoteric salts such as potassium bicarbonate, thermally labile blocked bases (i.e., components that chemically open upon heating and exhibit greater basicity, such as urethane), and the like have been investigated. While the addition of weakly basic substances has been suggested to improve the shelf life of formulations containing iodonium cationic initiators, such solutions do not provide stability to systems that are destabilized by extensive actinic radiation exposure. While some of these components, when added to iodonium-based cationic polymerizable compositions, reduce and sometimes eliminate runaway reactions after extensive actinic exposure at certain concentration levels, they also have a strong tendency to reduce wet strength in the imaged areas and inhibit curing from proceeding after imaging is completed. However, it was found that the addition of phenolic, phosphite or lactone antioxidants or combinations thereof (which are neutral or slightly acidic) reduces the tendency to thermal runaway and does not have a significant effect on wet strength or on curing after dark reaction.

Without being bound or limited by any theory, it is believed that the antioxidant provides stability by scavenging free radicals generated by actinic radiation exposure and those that may be thermally generated during a runaway exothermic reaction of the polymeric formulation. Thus, when an antioxidant is used, any acid generated as a result of actinic exposure (assuming insufficient free radical elimination during exposure) can still be used to initiate polymerization of the cationic polymerizable component. Thus, antioxidants can limit the initiation causes of run-away polymerization (i.e., photo-chemically and high-temperature thermally induced radical generation that results in new cationic species through radical attack (radial attack) of iodonium-based cationic initiators), but have little effect on residual cationic species generated as a result of imagewise photo-exposure.

In the photopolymer compositions contemplated by the present invention, the general components include epoxides, hydroxy-functional compounds, oxetanes (propylene oxide), (meth) acrylates, photoinitiators, free radical initiators, sensitizers, and other additives. Examples of each of these classes are described below. Various combinations thereof may be used as stereolithography compositions or compositions for other photoimaging applications.

The invention relates in particular to a composition comprising:

a) a cationic polymerizable compound;

b) an iodonium-based cationic initiator;

c) a photosensitizer for the cationic initiator; and

d) antioxidant selected from the group consisting of phenolic antioxidants, phosphate antioxidants, lactone antioxidants, wherein the amount of antioxidant is between 0.01 and 10% by weight relative to the total weight of the composition.

Cationic polymerizable compound

Epoxide compound

Epoxy-containing materials (substances), also referred to as epoxy materials, may be cationically curable. This means that the polymerization and/or crosslinking of the epoxy groups, as well as other reactions, can be initiated by cations. These materials may be monomers, oligomers or polymers. Such materials may have aliphatic, aromatic, cycloaliphatic, araliphatic (aryl) or heterocyclic structures; they may include epoxy groups as pendant groups or groups that form part of an alicyclic or heterocyclic ring system. Those types of epoxies include those commonly known and commercially available.

The composition may comprise one or more epoxides (epoxides). Preferably, the composition will comprise at least one liquid (at 23 ℃ C. at room temperature) component such that the combination of materials is a liquid. Thus, the epoxy-containing material is preferably a single liquid epoxy material, a combination of liquid epoxy materials, or a combination of a liquid epoxy material and a solid epoxy material, wherein the solid epoxy material is soluble in the liquid. However, in certain embodiments, for example, in embodiments in which the epoxy material is soluble in other components of the composition, the epoxy material may consist only of materials that are solid at room temperature. When a solid composition is used, the composition may be diluted or liquefied by applying shear and/or heat before or during use.

Examples of suitable epoxy materials include polyglycidyl and poly (methylglycidyl) esters of polycarboxylic acids, or poly (oxiranyl) ethers of polyethers. The polycarboxylic acid may be: aliphatic, such as glutaric acid, adipic acid, and the like; alicyclic, such as tetrahydrophthalic acid; or aromatic, such as phthalic acid, isophthalic acid, trimellitic acid, or pyromellitic acid. The polyether may be poly (tetrahydrofuran). These compounds may be used alone or in combination of two or more.

Other suitable epoxy materials also include polyglycidyl ethers or poly (methyl glycidyl) ethers obtained by reaction of a compound having at least one free alcoholic hydroxyl group and/or phenolic hydroxyl group and an appropriately substituted epichlorohydrin. The alcohol may be an acyclic alcohol such as ethylene glycol, diethylene glycol, and higher poly (oxyethylene) glycols; alicyclic, such as 1, 3-or 1, 4-dihydroxycyclohexane, bis (4-hydroxycyclohexyl) methane, 2-bis (4-hydroxycyclohexyl) propane, or 1, 1-bis (hydroxymethyl) cyclohex-3-ene; or contain an aromatic nucleus, such as N, N-bis (2-hydroxyethyl) aniline or p, p' -bis (2-hydroxyethylamino) diphenylmethane. These compounds may be used alone or in combination of two or more together.

Other suitable epoxy compounds include those which may be derived from mononuclear phenols, such as resorcinol or hydroquinone, or they may be based on polynuclear phenols, such as bis (4-hydroxyphenyl) methane (bisphenol F), 2-bis (4-hydroxyphenyl) propane (bisphenol a), or condensation products of phenols or cresols obtained under acidic conditions with formaldehyde, such as phenol novolacs and cresol novolacs. These compounds may be used alone or in combination of two or more together.

Suitable epoxy materials also include poly (N-glycidyl) compounds, which are obtained, for example, by dehydrochlorination of the reaction product of epichlorohydrin with an amine containing at least two amine hydrogen atoms, such as, for example, N-butylamine, aniline, toluidine, m-xylylenediamine, bis (4-aminophenyl) methane or bis (4-methylaminophenyl) methane. Suitable poly (N-glycidol) compounds also include N, N '-diglycidyl derivatives of cycloalkyleneureas, such as ethyleneurea or 1, 3-propyleneurea, and N, N' -diglycidyl derivatives of hydantoin, such as 5, 5-dimethylhydantoin. These compounds may be used alone or in combination of two or more together.

Examples of suitable epoxy materials include poly (S-glycidyl) compounds, which are di-S-glycidyl derivatives derived from dithiols such as ethane-1, 2-dithiol or bis (4-mercaptomethylphenyl) ether.

The epoxide-containing material may be selected from the group consisting of bis (2, 3-epoxycyclopentyl) ether, 2, 3-epoxycyclopentyl glycidyl ether, 1, 2-bis (2, 3-epoxycyclopentyloxy) ethane, bis (4-hydroxycyclohexyl) methane diglycidyl ether, 2-bis (4-hydroxycyclohexyl) propane diglycidyl ether, 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane, 3, 4-epoxy-6-methylcyclohexylmethyl-3, 4-epoxy-6-methylcyclohexanecarboxylate, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate, ethylenebis (3, 4-epoxycyclohexanecarboxylate), Ethylene glycol di (3, 4-epoxycyclohexylmethyl) ether, vinylcyclohexene dioxide, dicyclopentadiene diepoxides, α - (epoxyethylmethyl) - ω - (epoxyethylmethoxy) poly (oxy-1, 4-butanediyl), diglycidyl ether of neopentyl glycol, or 2- (3, 4-epoxycyclohexyl-5, 5-spiro-3, 4-epoxy) cyclohexane-1, 3-dioxane, and combinations thereof. These compounds may be used alone or in combination of two or more together.

However, it is also possible to use epoxides in which the 1, 2-epoxy groups are bonded to different heteroatoms or functional groups. Those compounds include, for example, N, O-triglycidyl derivatives of 4-aminophenol, glycidyl ether glycidyl esters of salicylic acid, N-glycidyl-N' - (2-glycidyloxypropyl) -5, 5-dimethylhydantoin, or 2-glycidyloxy-1, 3-bis (5, 5-dimethyl-1-glycidylhydantoin-3-yl) propane. Furthermore, liquid prereacted adducts of such epoxides with hardeners are suitable for the epoxides.

Additional epoxy materials include alicyclic diepoxides such as bis (4-hydroxycyclohexyl) methane diglycidyl ether, 2-bis (4-hydroxycyclohexyl) propane diglycidyl ether, 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, 3, 4-epoxy-6-methylcyclohexylmethyl-3, 4-epoxy-6-methylcyclohexanecarboxylate, bis (3, 4-epoxycyclohexylmethyl) adipate, bis (3, 4-epoxy-6-methylcyclohexylmethyl) adipate, ethylenebis (3, 4-epoxycyclohexanecarboxylate), ethylene glycol bis (3, 4-epoxycyclohexylmethyl) ether, 2- (3, 4-epoxycyclohexyl-5, 5-spiro-3, 4-epoxy) cyclohexane-1, 3-dioxane, and combinations thereof. These compounds may be used alone or in combination of two or more together.

The other epoxy compound comprises at least one cyclohexene oxide structure, preferably at least two cyclohexene oxide structures.

In the present invention, it is preferred that the composition comprises at least one glycidyl epoxy compound.

The epoxy material may have a molecular weight that varies over a wide range. In general, the epoxy equivalent, i.e., the number average molecular weight divided by the number of reactive epoxy groups, is preferably in the range of 60 to 1000.

The composition of the invention comprises from 10% to 99.5% by weight of one or more epoxides, relative to the total weight of the composition. In another embodiment, the composition of the invention comprises from 20% to 85% by weight of one or more epoxides, relative to the total weight of the composition.

Oxetanes

The following compounds are examples of oxetane compounds having one oxetane ring in the molecule: 3-ethyl-3-hydroxymethyloxetane, 3- (methyl) allyloxymethyl-3-ethyloxetane, (3-ethyl-3-oxetanylmethoxy) toluene, 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, [1- (3-ethyl-3-oxetanylmethoxy) ethyl ] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmeth) ether, and mixtures thereof, Isobornyl (3-ethyl-3-oxetanylmethyl) ether, 2-ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyldiethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, and mixtures thereof, Tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3-oxetanylmethyl) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether, and the like. These compounds may be used alone or in combination of two or more together.

Examples of the compound having two or more oxetane rings in the molecule are 3, 7-bis (3-oxetanyl) -5-oxa-nonane, 3' - (1, 3- (2-methylene) propanediylbis (oxymethylene)) bis- (3-ethyloxetane), 1, 4-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, 1, 2-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] ethane, 1, 3-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] propane, ethylene glycol di (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl-3-oxetanylmeth) ether, Triethylene glycol di (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol di (3-ethyl-3-oxetanylmethyl) ether, tricyclodecanedimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tri (3-ethyl-3-oxetanylmethyl) ether, 1, 4-bis (3-ethyl-3-oxetanylmethoxy) butane, 1, 6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tri (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetra (3-ethyl-3-oxetanylmethyl) ether, polyethylene glycol di (3-ethyl-3-oxetanylmethoxy) ether, polyethylene, Dipentaerythritol hexa (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol penta (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol tetra (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexa (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol penta (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropane tetra (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, and mixtures thereof, EO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, PO-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, EO-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether, and the like. These compounds may be used alone or in combination of two or more together.

Among the above compounds, oxetane compounds having 1 to 10, preferably 1 to 4, and particularly preferably two oxetane rings in the molecule are suitable. Specifically, (3-ethyl-3-oxetanylmethoxy) toluene, 1, 4-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, 1, 2-bis (3-ethyl-3-oxetanylmethoxy) ethane and trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether were used. These compounds may be used alone or in combination of two or more together.

The composition of the invention may comprise, relative to the total weight of the composition, from 5% to 80% by weight of one or more oxetanes. It may also comprise, relative to the total weight of the composition, from 10% to 60% by weight of one or more oxetanes.

Hydroxy-functional compounds

The composition of the invention may comprise a hydroxy-functional compound.

The hydroxyl-containing material used in the present invention may be any suitable organic material having a hydroxyl functionality of at least 1, and preferably at least 2. The material is preferably substantially free of any groups that negatively interfere with the curing reaction or are thermally or photolytically unstable. These compounds may be used alone or in combination of two or more.

Any hydroxyl group can be employed for a particular purpose. Preferably, the hydroxyl containing material comprises two or more primary or secondary aliphatic hydroxyl groups. The hydroxyl group may be intramolecular or terminal. Monomers, oligomers or polymers may be used. The hydroxyl equivalent weight, i.e., the number average molecular weight divided by the number of hydroxyl groups, is preferably in the range of 31 to 5000. These compounds may be used alone or in combination of two or more.

Representative examples of hydroxyl-containing materials having a hydroxyl functionality of 1 include alkanols, monoalkylethers of polyoxyalkylene glycols, monoalkylethers of alkylene glycols, and others, and combinations thereof.

Representative examples of useful monomeric polyhydroxy organic materials include alkylene and aralkylene diols and polyols, such as 1, 2, 4-butanetriol, 1, 2, 6-hexanetriol, 1, 2, 3-heptanetriol, 2, 6-dimethyl-1, 2, 6-hexanetriol, (2R, 3R) - (-) -2-benzyloxy-1, 3, 4-butanetriol, 1, 2, 3-hexanetriol, 1, 2, 3-butanetriol, 3-methyl-1, 3, 5-pentanetriol, 1, 2, 3-cyclohexanetriol, 1, 3, 5-cyclohexanetriol, 3,7, 11, 15-tetramethyl-1, 2, 3-hexadecanetriol, 2-hydroxymethyltetrahydropyran-3, 4, 5-triol, 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, 1, 3-cyclopentanediol, trans-1, 2-cyclooctanediol, 1, 16-hexadecanediol, 3, 6-dithia-1, 8-octanediol, 2-butyne-1, 4-diol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 7-heptanediol, 1, 8-octanediol, 1, 9-nonanediol, 1-phenyl-1, 2-ethanediol, 1, 2-cyclohexanediol, 1, 5-decalindiol, 2, 5-dimethyl-3-hexyne-2, 5-diol, 2, 7-dimethyl-3, 5-octadiyne-2, 7-diol, 2, 3-butanediol, 1, 4-cyclohexanedimethanol, and combinations thereof.

Representative examples of useful oligomeric and polymeric hydroxyl-containing materials include polyoxyethylene and polyoxypropylene diols and triols having molecular weights of from about 200 to about 10,000; polybutylene glycols of different molecular weights; poly (oxyethylene-oxybutylene) random or block copolymers; copolymers comprising pendant hydroxyl groups formed by hydrolysis or partial hydrolysis of vinyl acetate copolymers; a polyvinyl acetal comprising pendant hydroxyl groups; hydroxyl terminated polyesters and hydroxyl terminated polylactones; hydroxy-functionalized polyalkadienes, such as polybutadiene; aliphatic polycarbonate polyols such as aliphatic polycarbonate diols; and hydroxyl terminated polyethers; and combinations thereof.

Other hydroxyl containing monomers include 1, 4-cyclohexanedimethanol and aliphatic and cycloaliphatic monohydroxy alkanols. Other hydroxyl-containing oligomers and polymers include hydroxyl and hydroxyl/epoxy functionalized polybutadiene, polycaprolactone diols and triols, ethylene/butylene polyols, and monohydroxy functional monomers. Examples of polyether polyols are polypropylene glycols and glycerol propoxylate-B-ethoxylate triols of various molecular weights. Further examples include linear and branched polytetrahydrofuran polyether polyols of different molecular weights, such as in the range of 150-4000g/mol, preferably in the range of 150-1500g/mol, more preferably in the range of 150-750 g/mol.

The composition of the invention may comprise, relative to the total weight of the composition, from 1% to 60% by weight of one or more polymerizable hydroxy-functional compounds. It may also comprise, relative to the total weight of the composition, from 5% to 40% by weight of one or more polymerizable hydroxy-functional compounds. It may further comprise, relative to the total weight of the composition, from 10% to 25% by weight of one or more polymerizable hydroxy-functional compounds.

(meth) acrylic acid esters

One component that can be used in the composition of the present invention may be a polymer (copolymer) obtained by (co) polymerizing a monomer comprising at least one (meth) acrylate group or a monomer mixture comprising at least one monomer comprising a (meth) acrylate group. Specifically, the component may be one or more polymers (copolymers) selected from (1) homopolymers of monomers comprising (meth) acrylate groups, (2) copolymers prepared from two or more monomers comprising (meth) acrylate groups, and (3) copolymers prepared from one or more monomers comprising (meth) acrylate groups and one or more other monomers copolymerizable with the monomers comprising (meth) acrylate groups.

As examples of suitable (meth) acrylates are given n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-aminohexyl (meth) acrylate, 2-heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl (meth) acrylate, cyclohexyl (meth) acrylate, and phenyl (meth) acrylate. Although these (meth) acrylates may be used alone, two or more of them are more suitably used in combination.

As the monomer other than the (meth) acrylic acid ester (copolymerizable monomer) used for preparing the copolymer, vinyl compounds such as vinyl acetate, styrene, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl toluene, and acrylamide can be given.

The ethylenically unsaturated monomer that can be used as a component in the composition of the present invention is a compound having an ethylenically unsaturated bond (C double-bonded to another C) in a molecule and includes a monofunctional monomer containing one ethylenically unsaturated bond and a polyfunctional monomer containing two or more ethylenically unsaturated bonds in one molecule, and preferably contains three or more ethylenically unsaturated bonds in one molecule.

Examples of the monofunctional monomer having one ethylenic unsaturated bond in the molecule include acrylamide, (meth) acryloylmorpholine, 7-amino-3, 7-dimethyloctyl (meth) acrylate, isobutoxymethyl (meth) acrylamide, isobornyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, tert-octyl (meth) acrylamide, diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dodecyl (meth) acrylate, dicyclopentadiene (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, N-dimethyl (meth) acrylamide, N-dimethyl (meth) acrylate, N-ethyl (, Tetrachlorophenyl (meth) acrylate, 2-tetrachlorophenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrabromophenyl (meth) acrylate, 2-tetrabromophenoxyethyl (meth) acrylate, 2-trichlorophenoxyethyl (meth) acrylate, tribromophenyl (meth) acrylate, 2-tribromophenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, vinylcaprolactam, N-vinylpyrrolidone, phenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, pentachlorophenyl (meth) acrylate, pentabromophenyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, bornyl (meth) acrylate and methyltriethylene diethylene glycol (meth) acrylate, polypropylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, and propylene glycol mono (meth) acrylate, And compounds represented by the following chemical formulae (28) to (30). These compounds may be used alone or in combination of two or more.

As examples of commercially available products of these monofunctional monomers, ARONIX M-101, M-102, M-111, M-113, M-117, M-152, TO-1210 (manufactured by Toagosei Co., Ltd.), KAYARAD TC-110S, R-564, R-128H (manufactured by Nippon Kayaku Co., Ltd.), Viscoat 192, 220, 2311HP, 2000, 2100, 2150, 8F, 17F (manufactured by Osaka Organic Chemical Industry Co., Ltd.), and the like can be listed.

Examples of the polyfunctional monomer having two or more ethylenically unsaturated bonds in one molecule include ethylene di (meth) acrylate, dicyclopentenyl di (meth) acrylate, triethylene glycol diacrylate, tetraethylene glycol di (meth) acrylate, tricyclodecanediyldimethylenedi (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, ethylene glycol di, Both-end (meth) acrylate adduct of bisphenol A diglycidyl ether, 1, 4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyester di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol tetra (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol penta (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, EO-modified hydrogenated bisphenol A di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (, PO-modified hydrogenated bisphenol A di (meth) acrylate, EO-modified bisphenol F di (meth) acrylate, and (meth) acrylate of phenol novolac polyglycidyl ether. These compounds may be used alone or in combination of two or more together.

As examples of commercially available products of these polyfunctional monomers, SA1002 (manufactured by Mitsubishi Chemical Corp., Ltd.), Viscoat 195, 230, 260, 215, 310, 214HP, 295, 300, 360, GPT, 400, 700, 540, 3000, 3700 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), KAYARADR-526, HDDA, NPGDA, TPGDA, MANDA, R-551, R-712, R-604, R-684, PET-30, GPO-303, TMPTA, THE-330, DPHA-2H, DPHA-2C, DPHA-21, TPA-310, D-330, DPCA-20, DPCA-30, TPA-60, TPA-120, DN-0075, 2475, T-1420, T-2020, T-320, TPA-0, TPA-1040, TPA-20, TPA-2040, TPA-330, TPA-120, TPA-0075, TPA-1420, TPA-75, TPA-2, TPA, R-011, R-300, R-205 (manufactured by Nippon Kayaku Co., Ltd.), ARONIX M-210, M-220, M-233, M-240, M-215, M-305, M-309, M-310, M-315, M-325, M-400, M-6200, M-6400 (manufactured by Toagosei Co., Ltd.), Lite Acrylate BP-4EA, BP-4PA, BP-2EA, BP-2PA, DCP-A (manufactured by Kyoei Chemical Co., Ltd.), New Frontier BPE-4, TEICA, BR-42M, GX-8345 (manufactured by Daiichi Kogyaku Co., Ltd.), ASF-400 (manufactured by Nippon Steel Co., Shol Co., Ltd.), Riboku SP-1506, RiboyVR-1507 SP-15077, HihogHCP-15077, Sp-60 SP, M-315, M-400, M-4010, M-6400 (manufactured by Toagosei Co., Ltd.), New Frontier BPE-4, TEICA, Te, Sp, R-42, R-5, R-X-, ltd., manufactured), NK Eater a-BPE-4 (manufactured by Shin-nakamura chemical co., ltd.), and the like.

These polyfunctional monomers having three or more ethylenically unsaturated bonds may be selected from the group consisting of the above-mentioned tri (meth) acrylate compounds, tetra (meth) acrylate compounds, penta (meth) acrylate compounds, and hexa (meth) acrylate compounds. Among these compounds, trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, and ditrimethylolpropane tetra (meth) acrylate are particularly preferable. These compounds may be used alone or in combination of two or more together.

The composition of the invention comprises, relative to the total weight of the composition, from 0% to 50% by weight of one or more (meth) acrylates. It may also comprise 6 to 40 wt% of one or more (meth) acrylates.

Cationic photoinitiators

Any suitable type of photoinitiator that forms cations upon exposure to actinic radiation that initiate the reaction of cationically polymerizable compounds (e.g., epoxy materials) may be used in the compositions according to the present invention. There are a large number of cationic photoinitiators which are known and have proven suitable in the art. They include, for example, onium salts with anions of weak nucleophilicity. Examples are halonium salts (halonium salt), iodosyl salts (iodosyl salt) or sulfonium salts, as described in published european patent applications EP 153904 and WO 98/28663, sulfoxonium salts, as described in published european patent applications EP 35969, 44274, 54509, and 164314, or diazonium salts, as described in U.S. Pat. nos. 3,708,296 and 5,002,856. Other cationic photoinitiators are metallocene salts, as described in published European applications EP 94914 and 94915, which are incorporated herein by reference in their entirety.

Preferred cationic photoinitiators include iodonium photoinitiators, e.g., iodine tetrakis (pentafluorophenyl) borate, as they tend to be less yellow, especially when used in conjunction with a photosensitizer. Other suitable iodonium initiators are described in detail in WO 2005/070989, the entire contents of which are incorporated herein by reference.

The composition of the invention may comprise, relative to the total weight of the composition, from 0.1% to 15% by weight of one or more cationic photoinitiators, preferably from 0.3% to 10% by weight for a sulfonium type initiator/solvent cationic initiator. Where the composition includes an iodonium cationic initiator, about 0.1 to 5 wt%, and preferably 0.25 to 3 wt% of the active initiator is used.

Sensitizers

Sensitizers may also be used, depending on the type of initiator, in order to increase the light efficiency, or to sensitize the cationic photoinitiator to a particular wavelength, such as a particular laser wavelength or a particular series of laser wavelengths. Examples of sensitizers are polycyclic aromatic hydrocarbons or aromatic ketone compounds. Specific examples of preferred sensitizers can be found in published european patent application EP 153904, the entire content of which is incorporated herein by reference. Other preferred sensitizers are benzoperylene, 1, 8-diphenyl-1, 3, 5, 7-octatetraene, and 1, 6-diphenyl-1, 3, 5-hexatriene, as described in U.S. Pat. No. 5,667,937, the entire contents of which are incorporated herein by reference. It will be appreciated that additional factors in the choice of sensitizer are the nature and dominant wavelength of the source of actinic radiation. Other preferred photosensitizers are isopropylthioxanthone, chlorothioxanthone, other substituted thioxanthones, and 4-benzoyl-4' -methylbenzhydryl sulfide. For use in stereolithography, 4-benzoyl-4' -methylbenzene sulfide (BMS) is most preferred due to low color formation and low absorption below 400 nm. Other suitable sensitizers are described in detail in WO 2005/070989, the entire contents of which are incorporated herein by reference.

The concentration of photosensitizer in a formulation depends on a number of other factors such as: the presence of other absorbing species, e.g., photoinitiators, monomers, and dyes, etc.; the presence of a light scattering component; the wavelength used in the system; the depth of polymerization to be achieved; polarity of the solvent; the degree and type of substitution at the photosensitizer moiety; bleaching or darkening caused by dissociation or addition of an absorbent; as well as other factors. In general, it is preferred to have a concentration of photosensitizer that provides a depth of penetration (commonly referred to as D in the field of stereolithography)_p) About the thickness of a layer of the composition applied to the surface, or the depth to which the polymerization is to be effected by actinic exposure. Preferably, the photosensitizer used in the composition of the present invention is to achieve a D between about 0.005cm and about 0.03cm_p. For example, if the coating thickness is about 0.015cm, the Dp of the composition is preferably about 0.005-0.025 cm. To achieve the preferred Dp range of about 0.005cm to 0.03cm, it is preferred to use 4-benzoyl-4' -methylbenzene sulfide (BMS) in a transparent nonabsorbing monomer, without further initiator, absorber, or light scattering elements, with an operating wavelength range of, for example, 313-365nm, at a concentration of 0.12 wt% to 0.85 wt%. However, if other absorbers, initiators, light scattering components, etc. are present, it is preferred to use lower concentrations. Such concentrations may be as low as about 0.01 wt% to about 0.8 wt%. The total amount of photosensitizer used is in the range of about 0.01 wt% to about 1.0 wt% relative to the weight of the unfilled (i.e., devoid of filler, such as glass) composition.

In the present invention, it is preferred to use a photosensitizer and other initiator such that Dp is less than the thickness of the coating or within the preferred range of lower Dp. A lower Dp (higher absorption) causes the actinic light to be absorbed closer to the exposed photopolymer surface, thus resulting in a vanishing "activated" volume (presumably the depth of exposure times the exposed photopolymer surface) and in turn less exothermic reaction of polymerization. In addition, the heat generated by the exothermic reaction at the surface is more likely to be dissipated to the environment than to unexposed portions of the composition.

Free radical photoinitiators

The composition may employ a photoinitiator which forms free radicals when suitably irradiated. Typical compounds of known photoinitiators are benzoins (benzoins), such as benzoin, benzoin ethers, such as benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether, benzoin phenyl ether, and benzoin acetate, acetophenones, such as acetophenone, 2, 2-dimethoxyacetophenone, 4- (phenylthio) acetophenone, and 1, 1-dichloroacetophenone, benzil (benzil), benzil ketals, such as benzil dimethyl ketal, and benzil diethyl ketal, anthraquinones, such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, and 2-amylanthraquinone, and also triphenylphosphine, benzoylphosphine oxides, such as 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide (Lucins TPO), phenones, such as benzophenone, and 4, 4 ' -bis (N, N ' -dimethylamino) phenone, thioxanthone and xanthone, acridine derivatives, phenazine derivatives, quinoxaline derivatives or 1-phenyl-1, 2-propanedione-2-O-benzoyl oxime, 1-aminophenyl ketones or 1-hydroxyphenyl ketones, such as 1-hydroxycyclohexyl benzophenone, phenyl (1-hydroxyisopropyl) ketone and 4-isopropylphenyl (1-hydroxyisopropyl) ketone, or triazine compounds, for example 4 ' -methylthiophenyl-1-bis (trichloromethyl) -3, 5-S-triazine, S-triazine-2- (stilbene) -4, 6-bistrichloromethyl, and paramethoxystyryl triazine, all these compounds are known compounds. These compounds may be used alone or in combination of two or more together.

Suitable free-radical photoinitiators, which are usually used together with He/Cd lasers (operating at, for example, 325 nm), argon ion lasers (operating at, for example, 351nm, or 351 and 364nm, or triple-frequency YAG solid-state lasers (having an output of 349 or 355 nm) as radiation sources, are acetophenones, such as 2, 2-dialkoxyphenones and 1-hydroxyphenyl ketones, for example 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-1- {4- (2-hydroxyethoxy) phenyl } -2-methyl-1-propanone, or 2-hydroxyisopropylphenyl ketone (also known as 2-hydroxy-2, 2-dimethylacetophenone), but especially 1-hydroxycyclohexylphenyl ketone. Another class of free radical photoinitiators includes benzil ketals, such as benzil dimethyl ketal. In particular alpha-hydroxyphenyl ketones, benzildimethyl ketals, or 2, 4, 6-trimethylbenzoyldiphenylphosphine oxides can be used as photoinitiators. These compounds may be used alone or in combination of two or more.

Another suitable class of free radical photoinitiators includes ionic dye-counter ion compounds, which are capable of absorbing actinic radiation and generating free radicals, which can initiate polymerization of acrylates. Thus, the composition according to the invention, which comprises an ionic dye-counterion compound, can be cured in a more variable manner with visible light in the tunable wavelength range from 400 to 700 nm. Ionic dye-counter ion compounds and their mode of action are known, for example from published european patent application EP 223587 and U.S. Pat. nos. 4,751,102, 4,772,530 and 4,772,541.

Other free radical photoinitiators include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-dimethoxyacetophenone, and 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide. These photoinitiators tend to be less yellow than others.

In the case of the present invention, which comprises an iodonium-based cationic photoinitiator, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Chivacure 173) and 1-hydroxycyclohexyl phenyl ketone are preferred as co-sensitizers with other photosensitizers such as ITX and BMS. In this regard, 2-hydroxy-2-methyl-1-phenyl-propan-1-one is most preferred for use in applications where wavelengths below 365nm are used for actinic exposure.

The composition of the invention may comprise, relative to the total weight of the composition, from 0.1% to 15% by weight, more preferably from 1% to 10% by weight, of one or more free-radical photoinitiators.

Antioxidant agent

Examples of phenolic antioxidants that can be used in the present invention include 2, 6-di-tert-butyl-p-cresol, stearyl (3, 5-dimethyl-4-hydroxybenzyl) -thioglycolate, stearyl β - (4-hydroxy-3, 5-di-tert-butylphenol) propionate, 2, 4, 6-tris (3 ', 5' -di-tert-butyl-4 '-hydroxybenzylthio) -1, 3, 5-triazine, distearoyl (4-hydroxy-3-methyl-5-tert-butyl) benzylmalonate, 2' -methylenebis (4-methyl-6-tert-butylphenol), 4 '-methylenebis (2, 6-di-tert-butylphenol), 2' -methylenebis [6- (1-methylcyclohexyl) -p-cresol ], ethylene glycol bis [3, 5-bis (4-hydroxy-3-tert-butylphenyl) butyrate ], 4 ' -butylidenebis (6-tert-butyl-m-cresol), 2 ' -ethylidenebis (4, 6-di-tert-butylphenol), 2 ' -ethylidenebis (4-sec-butyl-6-tert-butylphenol), 1, 3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) -butane, bis [ 2-tert-butyl-4-methyl-6- (2-hydroxy-3-tert-butyl-5-methylbenzyl) phenyl ] terephthalate, 1, 3, 5-tris (3, 5-di-tert-butyl-4-hydroxybenzyl) -2, 4, 6-trimethylbenzene, 2, 6-diphenyl-4-octadecyloxyphenol, tetrakis [ methylene-3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] methane, 2-octylthio-4, 6-bis (4-hydroxy-3, 5-di-tert-butyl) phenoxy-1, 3, 5-triazine, 4' -thiobis (6-tert-butyl-m-cresol), stearyl β - (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionate, and triethylene glycol bis [ β - (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate ]. Preferred phenolic antioxidants are butylated hydroxytoluene, propyl gallate, tert-butylhydroquinone, butylated hydroxyanisole, 4 '- (2, 3-dimethyltetramethylene dicatechol), alpha tocopherol, thiodiethylene bis- (3, 5-di-tert-butyl-4-hydroxy) phenylpropionate, and tetrakis (methylene-3 (3', 5 '-di-tert-butyl-4' -hydroxyphenyl) propionate) methane.

Although the amount of phenolic antioxidant used in the iodonium-based composition depends on the molecular weight and number of phenolic groups, the amount of phenolic antioxidant is between 0.01 and 10 wt%, relative to the total weight of the composition. In another embodiment, 0.01 to 2 wt% of phenolic antioxidant is used, relative to the total weight of the composition. In another embodiment, 0.02 wt% to 0.1 wt% of phenolic antioxidants may be used to maintain the iodonium based composition with reasonably good to excellent wet strength (green strength).

Examples of phosphite antioxidants are tetrakis (2, 4-di-tert-butylphenyl) [1, 1-diphenyl ] -4, 4 '-diyl diphosphonite, tris (2, 4-di-tert-butylphenyl) phosphite, pentaerythrityl bis- (2, 4-di-tert-butylphenol) diphosphite, trisnonylphenyl phosphite, distearoylpentaerythrityl diphosphite, pentaerythrityl bis (2, 4-dicumylphenyl) diphosphite, 2' -ethylidenebis (4, 6-di-tert-butylphenyl) fluorophosphonite, other phosphite antioxidants and any combination with phenolic antioxidants and lactone antioxidants.

The amount of phosphite antioxidant is between 0.01% and 10% by weight relative to the total weight of the composition. In another embodiment, the amount of phosphite based antioxidant is between 0.01 wt% and 2 wt%. In another embodiment, the amount of phosphite based antioxidant is between 0.1 wt% and 2 wt%, preferably between 0.1 wt% and 1 wt%.

Examples of lactone-type antioxidants are 5, 7-di-tert-butyl-3- (3, 4-dimethylphenyl) -3H-benzofuran-2-one, 2(3H) -benzofuranone, 5, 7-bis (1, 1-dimethylethyl) -3-hydroxy RX (o) xylene, and other 2-phenylbenzofuran-2-one lactones.

The amount of lactone based antioxidant is between 0.01 and 10 wt% with respect to the total weight of the composition. In another embodiment, the amount of lactone based antioxidant is between 0.01 wt% and 2 wt%. In another embodiment, the amount of lactone based antioxidant is preferably between 0.02 wt% and 0.1 wt%, relative to the total weight of the composition.

All of these antioxidants may be used alone or in combination. Phenolic antioxidants are preferred antioxidants if used alone.

If used in combination, a combination of phenolic and phosphite antioxidants or phenolic and lactone antioxidants is preferred. If a lactone antioxidant is used in conjunction with a phenolic antioxidant, it is preferred to use the lower range of antioxidants in their respective preferred amounts.

Additive agent

Additives may also be present in the compositions of the present invention. Acid scavenging stabilizers are often added to compositions to prevent viscosity increases, such as during use in a stereo imaging process. Preferred acid scavenging stabilizers include those described in U.S. Pat. No. 5,665,792, the entire disclosure of which is incorporated herein by reference. Such acid scavenging stabilizers are typically hydrocarbon carboxylates of group IA and IIA metals. Preferred examples of such salts are sodium bicarbonate, potassium bicarbonate, and rubidium carbonate. Rubidium carbonate is preferred for the formulations of the present invention, with recommended amounts of 0.0015 to 0.005% by weight of the composition. Alternative acid scavenging stabilizers are polyvinylpyrrolidone and polyacrylonitrile. Other possible additives include dyes, pigments, fillers (e.g., silica particles, preferably amorphous silica particles, glass beads, or talc), wetting agents, photosensitizers for free-radical photoinitiators, leveling agents, surfactants, and the like.

The curing radiation is preferably in the range of 280-650 nm. Any convenient source of actinic radiation may be used, but lasers are particularly suitable. In the field of stereolithography, useful lasers include HeCd lasers, argon lasers, and triple frequency NdYAG lasers. The irradiation energy is preferably 10-150mJ/cm²Within the range of (1).

The specific embodiments disclosed herein are to be considered as illustrative. Various modifications in addition to those described will no doubt occur to those skilled in the art and such modifications are to be understood as forming a part of the present invention when they are within the spirit and scope of the appended claims.

Examples

In these examples, the Petri dishes used were of the polystyrene 60X 15mm type, under the trade name polystyrene351007 and manufactured by Becton Dickinson. In some cases, 15 grams of the formulation was added to the petri dish while in other cases 20 grams of the solution was used. The density of the resin was about 1.13 g/l. In the case of the Petri dish, the coating thickness (or depth) for the 15 g sample was approximately 0.47cm and the coating thickness (or depth) for the 20 g sample was approximately 0.63 cm.

In the following examples, representative components in the exemplary compositions are:

FIG. 1 aka formula I

Epon 825 was obtained from Resolution Performance co., Houston Tex. UVR6105 is obtained from Dow, Danbury CT. Grilonit F713 was obtained from EMS-Chemie, Sumter, s.c. Rhodorsil 2074 was obtained from Rhodia Silicones s.a.s, Lyon, france. OXT-101 was obtained from Toa Gosei in Japan. Chivacure BMS and Chivacure 173 were obtained from Chitec Chemical co. ITX or isopropylthioxanthone, PVP, BHT, and propyl gallate were obtained from Aldrich, WI, Milwaukee. DPHA was obtained from Sartomer, Exton, PA. Vikolox 14 was obtained from ElfAtochem, Philadelphia PA. PolyFox 6520 was obtained from Omnova Solutions, Akron, OH. BYK-361-N is obtained from BYK-Chemie, Wallingford, Connecticut. IR-1035, IR-1010. HP-136 andmaterials were obtained from Ciba Specialty Chemicals Corporation, Tarrytown, NY. BHT asAvailable from Degussa Fine Chemicals, Parsippany, NJ. Longnox 10 was obtained from Longchem International, Taipei, taiwan.

Preparation of the composition

The comparative examples and examples in tables 1 and 2 were prepared by mixing the components used in each composition until all the components were dissolved. These examples are representative of photoimageable compositions that may be used, for example, in stereolithography processes.

Test method

Exposure stability test:

the exposure stability test was used to evaluate the reduction of runaway reaction when phenolic and/or lactone antioxidants were used. In the exposure stability test for comparative example 1 and examples 1-12, a base composition was prepared and a specific amount of antioxidant was added to the base composition, which was then dissolved into a uniform example solution. The example solutions were then weighed and placed in petri dishes. The solution from each Petri dish was exposed to PCA (using a10 Phillips TLK40W/05 fluorescent bulb, which was used for 120 to 190 hours) for approximately 10 minutes. The sample was placed on a crown glass plate.

For Table I, comparative example 1 and examples 1-12, the rating "fail" indicates that the formulation turned brown or began to darken and smoke within a10 minute exposure period. By "acceptable" is meant that the formulation sample does not turn brown, darken, or smoke during the 10 minute exposure period.

From experiments, it is evident that the addition of phenolic, phosphite and/or lactone antioxidants helps to reduce run away polymerization when exposed to actinic flood exposure. It is also noted that increasing the amount of phenolic or lactone antioxidants eventually makes the sample accessible to petri dish tests. Furthermore, it is evident that the combination of phenolic and lactone antioxidants can be used to reduce run away polymerization when exposed to actinic flood exposure. It is possible that even if a formulation passes the 15 gram petri dish sample test, it may not pass the 20 gram petri dish test.

Exposed strip wet strength test

The exposed strip wet strength was judged by first pouring the composition into a petri dish and then scanning a rectangular strip of approximately 12.2 x 76.2mm on the surface using a solid state laser (operating at UV about 355 nm). 1/e of the collected light beam²The spot diameter is about 0.22mm and produces an image parallel to the scan line length. The distance between the scan lines is about 0.051mm and the total dose for all strips is about 35mJ/cm². Wet strength is obtained by pressing a metal doctor blade into the strip surface. A "poor" wet strength strip will be easily deformed by the doctor blade and will be brittle or easily break when the doctor blade is pressed in and moved sideways. This is the typical state in formulations where the radical/acrylate polymerization of the exposed strip has started but the cationic polymerization has been inhibited or slowed. A "good" wet strength strip is still fairly soft but will have more integrity when the doctor blade is pressed in and moved sideways. That is, the strip is not brittle but may still tear under mild force. This state indicates that the cationic polymerization has progressed to the point where the bars had moderate integrity. "good" wet strength strips are moderately soft and require some force to tear, e.g., several scratches of the surface. The "excellent" wet strength strip is rigid and can actually "click" when tapped with a spatula. Significant force is required to tear the strip, which is generally more prone to cracking than tearing. While the rolled strip properties vary from formulation to formulation, it is generally preferred that the wet strength be greater than the poor grade. However, if improved stability is desired,an improved balance between stability and wet strength, in such cases "good" to "good" wet strength and having "acceptable" exposure stability, is most preferred.

Photospeed detection

The following methods and formulations were used in the stereolithography process to achieve photospeed. The photospeed of the composition was measured by:

1. the petri dish of the composition was placed in an image plane within a stereolithography chamber having a temperature of about 30 ℃ and a relative humidity of about 30%.

2. The surface of the composition was exposed to a series of 6 shots, where each shot was a square (square) approximately 1.27cm on a side. The 6 shots were approximately 31.9, 40, 47.5, 59, 79, and 94.5mJ/cm². Irradiation was carried out with three times the frequency of a solid laser beam having an approximate wavelength output at the image plane of 354.7nm and a power of 115 mW. The laser beam was focused to about 0.022cm of the image plane and the laser had a pulse frequency of 80 kHz. Each irradiation was performed in a line-by-line manner in which the laser beam was scanned in the Y direction and then advanced in the X direction in increments of 0.0051 cm.

After 3.15 minutes, remove the squares from the petri dish and blot with paper towels. The thickness of each square was measured using a Mitutoyo Model NTD12-8# C digital spring loaded caliper.

4. The least squares fit line of the natural logarithm of the exposure to the measured thickness gives the listed values of the photosensing speed. Such characteristics are standard in stereolithography where Ec is the theoretical minimum energy to convert monomers to polymer, E10 is the actinic exposure energy required to form a10 mil (0.254mm) thickness, and Dp is the slope of the least squares fit line of the working curve.

5. In the case where the photospeed is relatively slow (i.e., the value of E10 is high), then a higher laser power is provided so that the average exposure yields a stripe thickness of about 0.254mm thickness.

TABLE I

TABLE 1

TABLE 1

Table 1 continues in the latter part of the present patent application.

To test the stability of comparative examples 2-5 and examples 13-39 in Table II, only 20 grams of Petri dish test was used. In each case, the onset of brown, black, or fuming (rather than assessing pass-fail) was recorded as the irradiation time to obtain a runaway reaction. A maximum of 20 min exposure was given for all samples. In all cases, the addition of antioxidant increased the time to runaway reaction and higher antioxidant levels further increased the settling time.

TABLE II

TABLE II

TABLE II

TABLE II

TABLE II

TABLE II

TABLE I continuation

TABLE I continuation

TABLE II

TABLE II

TABLE II

TABLE II

The resin composition of the present invention is preferably used in a layer-by-layer process in which a three-dimensional article is produced. Examples of such processes are: a stereolithography process; an inkjet process in which a photopolymer is ejected or extruded imagewise and exposed to actinic radiation to harden the photopolymer; an inkjet or extrusion process in which a non-actinic material is deposited onto the negative side of the image and a photopolymer is coated or sprayed onto the positive side of the image and subsequently or simultaneously exposed to actinic radiation to harden the photopolymer; a process similar to stereolithography, wherein illumination is through a mask or reflected off a mask, creating an exposure on a surface of the photopolymer or through a transparent surface, and wherein the exposure substantially hardens the photopolymer; and so on.

Within the chamber of the stereolithography apparatus, a vat of composition is provided, e.g., example 11, wherein a platen is positioned that is substantially coplanar with the surface of the vat of composition. The table was lowered below the surface of the composition and raised to about 0.02cm below the surface of the composition. The composition was then smoothed with a spatula to produce a substantially uniform layer of approximately 0.02cm thickness on the surface of the table.

Next, a layer of the composition was imagewise exposed, with an approximate wavelength output of 354.7nm and a power of 110mW at the image plane by means of tripling the frequency of the solid laser beam. At the surface of the image plane composition, the laser beam is focused to about 0.022cm 1/e²The laser beam diameter and the laser had a pulse frequency of 80 kHz. The irradiation is performed in a line-by-line manner in which the laser beam is scanned in the Y direction and then incremented in the X direction. The increments are approximately 0.0076cm apart. 71.23mJ/cm of composition is provided in the image area²To induce imagewise photohardening. Such irradiation can harden the composition to about 0.033 cm. Thus, the composition was given approximately 0.013cm more additional radiation than was needed to harden the 0.02cm layer. This is achieved bySuch additional irradiation may ensure adhesion to the table or to a previous layer.

After imagewise exposure, the table is lowered again below the surface of the composition so that unexposed composition can coat the table or previously exposed layer surface. The table was then raised so that the surface of the previously exposed layer was approximately 0.02cm below the surface of the composition. The doctor blade was again used to smooth the composition to form a layer having a thickness of approximately 0.02cm on the surface of the previously imaged layer. Then, a new value of about 71.23mJ/cm was added²The imagewise irradiation is provided to the surface of the composition. The process was continued until tensile bars (ASTM D638MType M1, approximately 1cm thick) were made. After preparation, the strips were removed from the bench, washed in propylene carbonate, rinsed in isopropanol, and then allowed to dry. Finally, the tensile bars were cured for 1 hour after PCA (from 3-D Systems). Other shaped parts were also prepared.

The stereolithography process described above was repeated using the base composition of example 11 to which 0.075% Irganox1035 was added. With the addition of Irganox1035, the parts were successfully prepared. The process can be used to make Quick-Cast models and to make molds. These molds may be used for applications such as injection molding and/or vacuum molding of thermoplastic sheets.

Although the invention has been illustrated and described herein with reference to certain specific embodiments, the invention is not to be limited to the details shown, but may be modified within the scope and range of equivalents of the claims without departing from the spirit of the invention.

Claims (20)

1. A cationic polymerizable composition comprising:

a) a cationic polymerizable compound;

b) an iodonium-based cationic initiator;

c) a photosensitizer for the cationic initiator; and

d) an antioxidant selected from the group consisting of phenolic antioxidants, phosphite antioxidants, lactone antioxidants, and combinations thereof, wherein the antioxidant is present in an amount between 0.01 wt% and 10 wt% relative to the total weight of the composition.

2. The composition of claim 1, wherein the antioxidant is a phenolic antioxidant and the phenolic antioxidant is present in an amount between 0.02 wt% and 0.1 wt%.

3. The composition of claim 1, wherein the antioxidant is a phosphite antioxidant and the phosphite antioxidant is present in an amount between 0.1 wt% and 1 wt%.

4. The composition of claim 1, wherein the antioxidant is a lactone-based antioxidant and the lactone-based antioxidant is present in an amount between 0.02 wt% and 0.1 wt%.

5. The composition of claim 1, wherein the cationic polymerizable compound comprises at least one compound containing an epoxy group, and an oxetane.

6. The composition of claim 1, further comprising a hydroxyl functional compound.

7. The composition of claim 1, further comprising a methacrylate.

8. The composition of claim 5, further comprising a free radical initiator.

9. The composition of claim 1, wherein the photosensitizer is 4-benzoyl-4' -methyldiphenylsulfide.

10. The composition of claim 1, wherein the photosensitizer is present in an amount to provide a depth of penetration (Dp) of about 0.005cm to about 0.03 cm.

11. The composition of claim 1, wherein the composition passes the exposure stability test.

12. A method of reducing the potential for run away polymerization in a process of exposing a polymerizable composition to actinic radiation, the method comprising mixing an amount of an antioxidant in an iodonium-based composition, wherein the amount of the antioxidant is sufficient to reduce the potential for run away polymerization when the composition is exposed to actinic radiation in bulk, wherein the antioxidant is selected from the group consisting of phenolic antioxidants, phosphite antioxidants, lactone antioxidants, and combinations thereof.

13. The method of claim 12, wherein the process is a stereolithography process.

14. A method for forming a cationically cured material comprising subjecting the cationically curable composition according to claim 1 to cationic curing conditions for a time sufficient to form a cured material from the composition.

15. A method for forming a three-dimensional article, comprising:

a) coating a layer of the cationically curable composition according to claim 1 on a surface;

b) imagewise exposing the layer to actinic radiation to form an imaged cross-section, wherein the radiation provides an exposure sufficient to cause substantial curing of the layer in the exposed areas;

c) coating a layer of the composition on the previously exposed imaged cross-section;

d) exposing the layer from step c) to imagewise actinic radiation to form an additional imaged cross-section, wherein the radiation has an intensity sufficient to substantially cure the layer in the exposed areas and to bond the layer to the previously exposed imaged cross-section; and

e) repeating steps c) and d) a sufficient number of times to produce the three-dimensional article.

16. The method of claim 15, wherein the article is a mold.

17. The method of claim 15, wherein the article is a mold.

18. A mold made from the composition of claim 1.

19. A mold made from the composition of claim 1, wherein the mold is an investment casting mold.

20. A method for manufacturing a three-dimensional article, comprising:

a) forming a mold from the composition of claim 1;

b) a thermoplastic sheet is formed on the mold by a vacuum forming technique.