Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
2002-07-11
2004-04-06
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S090000, C522S096000, C522S081000, C522S083000, C522S008000, C522S011000, C522S012000, C522S021000, C522S033000, C522S036000, C522S031000, C522S064000, C522S040000, C522S042000, C522S044000, C522S046000, C522S048000, C522S100000, C522S102000, C522S103000, C522S181000, C522S182000, C427S508000, C427S496000, C427S517000, C427S502000, C252S062540, C252S062580, C252S062640
Reexamination Certificate
active
06716893
ABSTRACT:
TECHNICAL FIELD
The present invention relates to ultraviolet light (uv) curable compositions capable of producing a ferromagnetic coating.
BACKGROUND OF THE INVENTION
Electronic components, such as capacitors and inductors, are typically applied to rigid circuit boards through the process of soldering. Electronic components may be produced applying curable compositions to a suitable substrate. Such film coatings have previously been formed through thermosetting and heat curing processes. Ferromagnetic materials are materials which can be permanently magnetized upon application of an external magnetic field. Ferromagnetic coatings in particular, as useful for forming such electronic components as inductors and capacitors.
Heat curable coatings require the use of organic solvents that contain a significant amount of volatile organic compounds (VOCs). These VOCs escape into the atmosphere while the heat curable coating dries. Such solvent based systems are undesirable because of the hazards and expenses associated with VOCs. The hazards include water and air pollution and the expenses include the cost of complying with strict government regulation on solvent emission levels. In contrast, UV curable ferromagnetic film coatings contain reactive monomers instead of solvents; thus eliminating the detrimental effects of the VOCs.
UV curable coatings are cured through rapid photo-induced polymerizations instead of thermal energy which releases VOCs into the atmosphere. Since the UV curing process is essentially solvent free, the necessity for time consuming and expensive pollution abatement procedures is greatly reduced.
UV curable coatings offer several other benefits not associated with thermally cured coatings. First, faster cure times offer substantial economic benefits. Furthermore, heat sensitive materials can be safely coated and cured with UV light without thermal degradation of heat sensitive substrates. Additionally, UV light is a relatively low cost of energy due to its widespread availability.
Although UV curable coatings are superior to their thermal counterparts, there are still disadvantages inherent in UV curable coatings. Since UV curable coatings require compositions with high molecular weight and viscosity, spray and brush application is often difficult. Additionally, many UV curable coatings require compositions that are prone to dispersion and instability.
Accordingly, there exists a need to provide environmentally safe UV curable ferromagnetic compositions which exhibit improved performance and workability. Additionally, there is a need to provide a method of applying an improved composition which furthers the goal of improved performance.
SUMMARY OF INVENTION
It is an object of the present invention to provide an improved composition that upon curing by ultraviolet light produces a ferromagnetic coating.
It is another object of the present invention to provide an improved ferromagnetic composition suitable for producing screen printed capacitors and inductors.
It is another object of the present invention to provide an improved ferromagnetic composition suitable for coating a suitable substrate that can be applied by spraying, screen printing, dipping, and brushing.
It is still another object of the present invention to provide an improved ferromagnetic composition that does not contain any significant amount of volatile organic solvents that do not become incorporated in the active layer after curing.
The present invention discloses an ultraviolet light curable ferromagnetic composition and method for making such a composition that may be used to produce a ferromagnetic coating on a suitable substrate. The disclosed composition does not contain any significant amount of volatile organic solvents that do not become incorporated in the active layer after curing. Specifically, the ferromagnetic composition contains 5% or less volatile organic solvents by weight.
In accordance with one aspect of the invention, an ultraviolet light curable ferromagnetic composition is provided. The ferromagnetic composition comprises a mixture of one or more aliphatic acrylated oligomers, a magnetic powder, and a photoinitiator. Preferably, the aliphatic acrylated oligomer mixture is present in an amount of about 15% to 45% of the total weight of the ferromagnetic composition, the photoinitiator is present in an amount of about 1% to 10% of the total weight of the ferromagnetic composition, and the magnetic powder is present in an amount of 20% to 60% of the total weight of the ferromagnetic composition. All percentages of the ferromagnetic composition as expressed in this document refer to the weight percentage of the stated component to the total weight of the ferromagnetic composition in its fluid state at standard temperature and pressure.
The ferromagnetic composition preferably further comprises an acrylated epoxy oligomer preferably present in an amount of about 2% to 6% of the total weight of the ferromagnetic composition and an unsaturated monomer preferably present in an amount of about 15% to 25% of the total weight of the ferromagnetic composition. The ferromagnetic composition may optionally include a flow promoting agent preferably in an amount of about 0.1% to 6% of the ferromagnetic composition.
In accordance with yet another aspect of the invention, a method is provided for depositing a ferromagnetic coating on a substrate. The method comprises a first step of applying to the substrate a ferromagnetic fluid-phase composition (“ferromagnetic composition”). The ferromagnetic composition comprises a mixture of one or more aliphatic acrylated oligomers, a magnetic powder, and a photoinitiator. Preferably, the aliphatic acrylated oligomer mixture is present in an amount of about 15% to 45% of the total weight of the ferromagnetic composition, the photoinitiator is present in an amount of about 1% to 10% of the total weight of the ferromagnetic composition, and the magnetic powder is present in an amount of 20% to 60% of the total weight of the ferromagnetic composition. The ferromagnetic composition preferably also includes an acrylated epoxy oligomer preferably present in an amount of about 2% to 6% of the total weight of the ferromagnetic composition, an unsaturated monomer preferably present in an amount of about 15% to 25% of the total weight of the ferromagnetic composition, and a flow promoting agent in an amount of about 0.1% to 6% of the total weight of the ferromagnetic composition.
The method also includes a second step of illuminating the ferromagnetic composition on the substrate with an ultraviolet light to cause the ferromagnetic composition to cure into the ferromagnetic coating.
In accordance with this method, the ferromagnetic composition can be selectively deposited on the substrate at specific locations where ferromagnetic plating is desired. It need not be applied to the entire substrate.
BEST MODE FOR CARRYING OUT THE INVENTION
Ferromagnetic Compositions
Reference will now be made in detail to presently preferred compositions or embodiments and methods of the invention, which constitute the best modes of practicing the invention presently known to the inventor.
In accordance with one aspect of the invention, a presently preferred ultraviolet light curable ferromagnetic composition (“ferromagnetic composition”) is provided. In this preferred embodiment, the ferromagnetic composition includes a mixture of one or more aliphatic acrylated oligomers. The aliphatic acrylated oligomer mixture is present in an amount of about 15% to 45% of the total weight of the ferromagnetic composition. The aliphatic acrylated oligomer mixture is more preferably present in an amount of about 25% to 35% of the total weight of the ferromagnetic composition, and most preferably about 30% of the total weight of the ferromagnetic composition. The aliphatic acrylated oligomer preferably comprises one or more urethane oligomers. Suitable aliphatic acrylated oligomers include Radcure Ebecryl 244 (aliphatic urethane diacrylate diluted 10% by weight with 1,6-hexanediol diacrylate),
Brooks & Kushman P.C.
McClendon S
UV Specialties, Inc.
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