Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making printing plates
Reexamination Certificate
2002-08-01
2004-09-14
Seidleck, James J. (Department: 1711)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making printing plates
C430S311000, C430S320000, C430S321000, C430S331000, C428S473500, C428S3550CN, C428S3550EN, C428S901000, C522S173000, C522S176000, C252S183110, C526S266000, C526S262000, C524S548000, C427S096400, C427S207100, C427S208200
Reexamination Certificate
active
06790597
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to thermosetting resin compositions and uses therefor. In a particular aspect, the present invention relates to thermosetting resin compositions containing maleimide resins, vinyl resins, or both.
BACKGROUND OF THE INVENTION
Bismaleimides per se occupy a prominent position in the spectrum of thermosetting resins. Indeed, several bismaleimides are commercially available. Bismaleimide resins are used as starting materials for the preparation of thermoset polymers possessing a wide range of highly desirable physical properties. Depending on the particular resin and formulation, the resins provide cured products having excellent storage stability, heat resistance, as well as good adhesive, electrical and mechanical properties. Accordingly, bismaleimide resins have been used for the production of moldings, heat-resistant composite materials, high temperature coatings and for the production of adhesive joints. Typically, however, in any particular resin formulation there is a trade-off between the various properties. For example, in the formulation of “snap” cure adhesives (i.e., adhesives that cure in two minutes or less at ≦200° C.), it is desirable to use a system which does not require the addition of diluent to facilitate handing. In other words, snap cure products require formulations containing 100% reactive materials. Thus, it is desirable to prepare snap cure resins which are liquid at or about room temperature (i.e., low viscosity materials) for ease of handling.
Unfortunately, up until now, it has not proved possible to formulate bismaleimide compositions that are both quick curing, easy to handle (i.e., liquid at or about room temperature), and have low moisture uptake. Consequently, it is a desideratum to provide thermosetting bismaleimide resin compositions that produce cured resins exhibiting a combination of highly desirable physical properties, including a combination of rapid curing and low water absorption.
A particular disadvantage of the use of bismaleimide resins for the types of applications described above is that, at room temperature, such materials exist as solid resins which require the addition of liquid diluents, in order for such resins to achieve a useful and processable viscosity. This difficulty has been compounded by the poor solubility of bismaleimides in organic solvents. This poor solubility generally necessitates the use of polar diluents, such as N-methyl-2-pyrrolidone or dimethylformamide. These diluents are undesirable, inter alia, from the viewpoint of environmental pollution. Therefore, it is another desideratum to provide bismaleimide resins that require little, if any, non-reactive diluent to facilitate handling.
One approach to solving the problem of a need for a diluent has been to use reactive liquid diluents. For example, the co-cure of simple bismaleimides with relatively simple divinyl ethers is known in the art. The use of such diluents is advantageous in that these materials become incorporated into the thermosetting resin composition, and hence do not create disposal problems. However, the range of suitable liquid reactive diluents is very limited. Many of the available diluents are restricted by the low boiling points thereof, and, therefore, the high volatility thereof; by the odor of such materials; by the toxicity of such materials and/or problems with skin irritation induced thereby; by the poor ability of such materials to solubilize bismaleimides; by the high viscosity of such materials, which, again, limits the bismaleimide solubility and also leads to little or no tack in the formulation; by the poor thermal stability and/or hydrolytic stability of such materials; by the incompatibility of such materials with other formulation modifiers, and the like. In particular, since the diluents become an integral component of the thermosetting resin composition, they necessarily influence its properties. Consequently, it is another desideratum to provide combinations of bismaleimide resins with reactive diluents which do not suffer from the above-described drawbacks and that produce cured resins exhibiting a combination of highly desirable physical properties, including rapid curing and low water absorption.
Accordingly, there has existed a definite need for bismaleimide resins that produce cured resins exhibiting a combination of highly desirable physical properties, including rapid curing and low water absorption. There has existed a further need for bismaleimide resins that require the additions of little, if any, non-reactive diluent to facilitate handling. And there has existed a still further need for combinations of bismaleimide resins with reactive diluents which do not suffer from the limitations of known reactive resins and that produce cured resins exhibiting a combination of highly desirable physical properties, including rapid curing and low water absorption. The present invention satisfies these and other needs and provides further related advantages.
BRIEF DESCRIPTION OF THE INVENTION
In accordance with the present invention, we have developed novel thermosetting resin compositions which meet all of the above-described needs, i.e., produce cured resins exhibiting a combination of highly desirable physical properties, including rapid curing and low water absorption, and which require little, if any, diluent to provide a system of suitable viscosity for convenient handling. In another aspect of the invention, we have developed novel combinations of bismaleimide resins with reactive diluents, which do not suffer from the limitations of known reactive resins and that produce cured resins exhibiting a combination of highly desirable physical properties, including rapid curing and low water absorption. The resulting cured resins are stable at elevated temperatures, are highly flexible, have low moisture uptake and good adhesion.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, there are provided novel maleimide resins of general formula I, as follows:
wherein:
m=1, 2 or 3,
each R is independently selected from hydrogen or lower alkyl, and
X is a monovalent or polyvalent radical selected from:
high molecular weight branched chain alkyl, alkylene or alkylene oxide species having from about 12 to about 500 atoms in the backbone thereof,
aromatic groups having the structure:
wherein:
n=1, 2 or 3,
each Ar is a monosubstituted, disubstituted or trisubstituted aromatic or heteroaromatic ring having in the range of 3 up to 10 carbon atoms, and
Z is a high molecular weight branched chain alkyl, alkylene or alkylene oxide species having from about 12 to about 500 atoms in the backbone thereof,
as well as mixtures thereof.
It is a distinct advantage of the bismaleimide resins of Formula I that they can be used with little, if any, added diluent. Generally, for easy handling and processing, the viscosity of a thermosetting resin composition must fall in the range of about 10 to about 12,000 centipoise, preferably from about 10 to about 2,000 centipoise. Maleimide resins of Formula I typically require no added diluent, or when diluent is used with resins contemplated by Formula I, far less diluent is required to facilitate handling than must be added to conventional maleimide-containing thermosetting resin systems. Preferred maleimide resins of Formula I include stearyl maleimide, oleyl maleimide and behenyl maleimide, 1,20-bismaleimido-10,11-dioctyl-eicosane (which likely exists in admixture with other isomeric species produced in the ene reactions employed to produce dimer acids from which the bismaleimide is prepared, as discussed in greater detail below), and the like, as well as mixtures of any two or more thereof.
When a diluent is added, it can be any diluent which is inert to the bismaleimide resin and in which the resin has sufficient solubility to facilitate handling. Representative inert diluents include dimethylformamide, dimethylacetamide, N-methylpyrrolidone, toluene, xylene, methylene chloride, tetrahydrofuran, methyl
Dershem Stephen M.
Osuna, Jr. Jose A.
Patterson Dennis B.
Bauman Steven C.
Henkel Corporation
McClendon Sanza L.
Seidleck James J.
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