Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
2000-07-19
2001-09-18
Thomas, Alexander S. (Department: 1772)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C428S319300
Reexamination Certificate
active
06291059
ABSTRACT:
FIELD OF INVENTION
The present invention relates to photo-polymerizable compositions comprising a cationically curable epoxy-containing monomer and a two-component initiator, more particularly, to such a composition comprising a two-component initiator which includes at least one salt of an organo-iron complex cation and at least one accelerator, and even more particularly to such a composition comprising an accelerator which, upon photo-activation, enables a color change in the epoxy-containing composition. The invention also relates to articles prepared using the noted composition.
BACKGROUND
Epoxy based compositions have been utilized in various applications, including the making of articles for use on motor vehicles. For example, these thermoset polymers are suitable for use in applications such as sealants, adhesives, moldings, and decorative features. Depending upon the application, such compositions have typically been either formed and cured prior to application on the vehicle or applied onto the vehicle and cured in place. Alternatively, some epoxy based compositions have been only partially cured prior to application on the vehicle and then additionally cured after being applied. The partially cured state of the epoxy composition provides dimensional stability to an article made with the composition and thus helps the article retain its shape during subsequent processing. The use of thermoset epoxy based compositions on motor vehicles often requires the curing of the epoxy under strict manufacturing timing constraints.
It is desirable for vehicle related articles produced from epoxy based compositions to match the color of other portions of the vehicle and, thereby, provide a desirable aesthetic appearance to the vehicle. The vehicle related articles produced from epoxy based compounds may be painted to match the color of other portions of the vehicle. Additionally, other epoxy based compositions that will not be painted may also require certain colors to match surrounding vehicle parts or to disguise the use of the epoxy based composition. The epoxy compositions do not always result in a desirable color upon polymerization.
It has typically been difficult for the epoxy portion of such articles to be painted “on-line” along with the rest of the vehicle because the paint is often brittle and tends to crack and flake off the surface of the epoxy portion of the article. This is particularly true with the electrostatically applied paint typically used in the automotive industry. In response to this problem, such articles have been painted “off-line” in a separate operation using specially formulated paints. The “off-line” application of a finished color coat does not always result in an adequate color match. Additionally, the portions of the vehicle to be painted are first primed with a base coat prior to the application of a finished color coat. The entire vehicle is then painted. Under these circumstances, if the color of the article does not closely match that of the primer, the painted article may appear different from that of the primed portions of the vehicle.
Alternatively, epoxy based compositions have been formulated with pigments to provide color matching with other portions of the vehicle. The utilization of pigments, however, can also result in an undesirable aesthetic difference between the article and the other portions of the vehicle. Additionally, the use of pigments in photo-polymerizable epoxy compositions may inhibit photo-polymerization.
Thus, it is desirable to provide an accelerator in an epoxy based composition in order to improve the curing time of the composition. Additionally, it is desirable to provide or impart specific colors to the cured, or partially cured, composition to achieve a desirable aesthetic appearance without adversely affecting the polymerization of the epoxy compositions.
SUMMARY OF THE INVENTION
The present invention relates to compositions comprising photo-polymerizable epoxy-containing monomers, where the polymerization of the monomers can be influenced by accelerators. The epoxy-containing monomers are energy-polymerized to form useful articles or coated articles. Preferably, the compositions are photo-polymerizable to achieve advantageous effects. In particular, the compositions of this invention, preferably, exhibit reduced time for polymerization while permitting an advantageous color change in the composition upon photo-activation.
Briefly, in one aspect, this invention provides a photo-polymerizable composition. The composition includes at least one photo-polymerizable epoxy-containing monomer and a two component initiator. The two component initiator includes at least one salt of an organo-iron complex cation and at least one accelerator. The composition can optionally include at least one of an alcohol-containing material and additional adjuvants, such as stabilizing ligands, thermoplastic resins, and coupling agents.
The inclusion of the accelerator of the present invention imparts a desirable color upon the polymerized epoxy composition. The color change is recorded as a change from an initial color at an un-polymerized state to a color measured in a polymerized state. The color change, as indicated by HunterLab color scale coordinates is indicated by an L value of 5 or more, and preferably, 15 or more.
In a further aspect, the invention provides a process for controlling or modifying the cure of a composition providing the polymerizable composition of the invention as previously described above. The composition is then subjected to a sufficient amount of energy, in the form of at least actinic energy, in order to polymerize the composition.
In yet a further aspect, this invention provides an article comprising a substrate having on at least one surface thereof a layer of the composition of the invention. The article is produced by providing a substrate, coating the substrate with the curable composition of the invention, and supplying sufficient energy to the composition in the form of at least actinic energy to polymerize the composition.
For purposes of the present invention, the following terms used in this application are defined as follows:
“energy polymerization” means curing or polymerization by means of thermal (infrared and heat) or actinic energy (ultraviolet, visible, or electron beam), or combinations thereof;
“photo-activation” means application of sufficient actinic energy to initiate the polymerization or cure;
“catalytically-effective amount” means a quantity sufficient-to effect polymerization of the curable composition to a polymerized product at least to a degree to cause an increase in viscosity of the composition under the conditions specified;
“initiator” and “catalyst” are used interchangeably and mean at least one salt of an organo-iron complex cation that can change the speed of a chemical reaction;
“cationically curable monomer” means at least one epoxide containing material;
“polymerizable composition” or “curable composition” as used herein means a mixture of the initiator system and the cationically curable monomer; alcohols and adjuvants optionally can be present;
“polymerize” or “cure” means to supply sufficient energy to a composition in the form of at least actinic energy to alter the physical state of the composition, to make it transform from a fluid to less fluid state, to go from a tacky to a non-tacky state, to go from a soluble to insoluble state, or to decrease the amount of polymerizable material by its consumption in a chemical reaction;
“photo-polymerize” means to polymerize through the application of at least actinic energy;
“B-staged” refers to an intermediate state in a thermosetting resin reaction in which the material softens when heated and swells, but does not dissolve in certain liquids, as described in ASTM Standard D907-91b, the material is partially cured (cross-linked) and dimensionally stable;
“initiation system”, “initiator system”, or “two-component initiator” means at least one salt of an organo-iron complex cation and at least one accelerator, the system
Johnson Michael A.
Mahoney Wayne S.
Willett Peggy S.
3M Innovative Properties Company
Knecht III Harold C.
Thomas Alexander S.
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