Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-08-27
2004-06-15
Reddick, Judy M. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C474S102000, C474S102000, C428S036900, C524S059000, C524S400000, C524S405000, C524S413000, C524S417000, C524S423000, C524S430000, C524S433000, C524S436000, C524S437000, C524S492000, C524S493000
Reexamination Certificate
active
06750280
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns thermosetting compositions based on polymers containing acid anhydride groups consisting essentially of a mixture of:
(A) a polymer containing acid anhydride groups,
(B) a molecular sieve being partially loaded with at least one amine
(C) a filler capable of releasing water upon heating at a temperature above the processing temperature of the mixture (A), (B) and (C).
BACKGROUND OF THE INVENTION
In the above compositions the amine is released from the molecular sieve B by the water of (C) above the dehydration temperature, then the polymer (A) is crosslinked by the amine.
The compositions of the invention can be made by mixing the components (A), (B) and (C) in an extruder or in any mixing apparatus under anhydrous conditions and below the amine-desorption and the dehydration temperature. The resulting mixture is thermoplastic and can be in the form of pellets. These pellets can be further used to make adhesives (hot melt adhesives (HMA)), to insulate electrical cables, to make tubes by extrusion or any object by injection moulding. Then crosslinking is achieved upon heating.
Prior art U.S. Pat. No. 5,792,816 discloses mixtures of polymer (A) and (B) molecular sieve being partially loaded with at least one amine and explains that release of amine for crosslinking of (A) can be achieved either (i) by intrusion of humidity or addition of water or water saturated solids or salts with crystal water either (ii) by warming the compositions to temperatures above the desorption temperature of the amine.
The desorption temperature of ethylene diamine adsorbed in 4A-molsieve is about 175° C. In some cases it is not desirable to warm as high as 175° C. to crosslink, it is more convenient to use the water desorbed from a filler. By choosing a proper filler this temperature can be adjusted.
The disadvantage of the above prior art is the difficulty to introduce water, saturated solids or salts with crystal water. The only reasonable way is intrusion of humidity.
Hot melt adhesives are enjoying increasing popularity in the bonding filed. They are solventless, and can be handled without pollution problems. In addition, they are suitable for production processes with short cycle times. The original disadvantage of hot melt adhesives, namely the poor bond strength at elevated temperature, has recently been overcome by using as hot melt adhesives reactive systems which when melted, react to provide materials which cannot be melted a second time or can be melted only at a much higher temperature.
On particularly important group of such a reactive hot melt adhesives are the moisture-crosslinking hot melts. Moisture-crosslinking hot melts are generally understood to be solventless adhesives which, after application to a substrate, acquire their ultimate strength and thermal stability under load by subsequent crosslinking by the action of water.
However, one disadvantage of hot melt adhesives which require the presence of water, is that the hardening reaction cannot take place completely, if at all, if the substrates to be bonded are impermeable to water vapor. The substrates could be steel sheets.
In the application of joint sealing compounds which post-crosslink in the presence of moisture, inadequate hardening or unsatisfactorily long hardening times are obtained when the joints to be sealed are bounded by substrates impermeable to water vapor.
DESCRIPTION OF THE INVENTION
The composition of the invention enable substrates impermeable to water vapor to be satisfactorily bonded with hot melts which post-crosslink in the presence of moisture.
Inventors have discovered that a filler capable of releasing water could be present in the composition.
The curing conditions of the present compositions are substantially independent of the ambient moisture conditions.
Depending on the filler, the present compositions are particularly suitable to make flame retarded insulating sheathings for electrical cables or floor coverings.
According to an advantageous embodiment of the invention the amine loaded molecular sieve (B) is dispersed in a nonreactive polymer (B1) and stored as a master batch under anhydrous conditions.
According to another advantageous embodiment of the invention the composition contains (D) a sufficient amount, typically 1 to 5%, of an unloaded molecular sieve to control the water content of the composition during storage of the masterbatch.
According to another advantageous embodiment of the invention the composition contains (E) a sufficient amount of a monofunctional acid anhydride compound to control the amine content of the composition and prevent preliminary crosslinking. The concentration of the monoanhydride is 0.5 to 10, preferably 2 to 5 equivalent percent of the content of anhydride groups in the polymers.
The addition of the stabilizers (D) and (E) prevents any of odor of amine and uncontrolled release.
The polymer (A) forming the reactive base of these compositions are solid or liquid polymers containing acid anhydride groups with molecular weights Mn of 500 to 1 000 000 Dalton. Polymers with a molecular weight Mn of 1000 to 500 000 Dalton are preferred. The polymers or oligomers contain at least 2 acid anhydride groups and have an acid number corresponding to the acid anhydride groups (determined with water-free alcoholic potassium hydroxide solution according to DIN 53 402) of 0.4 to 445 mg KOH/g. For example, this corresponds to a content of approximately 0.07 to 77 percent of weight of maleic acid anhydride, based on the weight of the functional polymer.
The acid anhydride groups can be distributed over the polymer molecule statistically or regularly or in the terminal position. The introduction of the acid anhydride groups can be achieved by means of copolymerisation, by reaction with terminally located reactive groups, by subsequent addition of unsaturated acid anhydrides onto individual or conjugated double bonds, or by means of graft reactions. The corresponding methods of synthesis are state of the art and disclosed in patent documents and the professional literature. A comprehensive overview of polymers containing acid anhydrides, their methods of synthesis and properties, and especially those which are synthesized using maleic acid anhydride, is contained in B. C. Trivedi and B. M Culbertson:
Maleic Anhydride
, Plenum Publ., New York (1982).
The polymers used according to the invention are preferably individual, or selected as a blend, from the group copolymers of unsaturated cyclic acid anhydrides, especially maleic or itaconic acid anhydride, with olefinic unsaturated monomers, for examples copolymers of acrylic acid and methacrylic acid esters with maleic and itaconic acid anhydride, addition products of unsaturated cyclic anhydrides on polymers with individual or conjugated double bonds, for example addition products of maleic acid anhydride on double bonds of polybutadienes, addition products of unsaturated cyclic acid anhydrides to styrene-butadiene rubber, thermoplastic styrene-butadiene and styrene-isoprene-block copolymers or to unsaturated decomposition products of high molecular weight natural rubbers, addition products of maleic acid anhydride on partially hydrogenated block copolymers of styrene-butadiene (e.g. SEBS), addition products of unsaturated cyclic acid anhydrides with polymers with mercaptan groups, for examples with an isocyanate prepolymer based urethane of mercaptoethanol, addition products which have been obtained by graft reactions of olefinic unsaturated cyclic acid anhydrides to polymers, for example graft products of maleic acid anhydride to a copolymer of ethylene with vinyl acetate or to a copolymer of ethylene, propylene and butene, polymeric ester-anhydrides or amine-anhydrides obtained through condensation of hydroxy- or aminofunctional polymers with trimellitic acid anhydride, pyromellitic acid anhydride, benzene-tetracarboxylic acid anhydride, benzophenone-tetracarboxylic acid anhydride or ethylene-bis-trimellitic acid anhydride.
The acid anhydride groups can be contained onl
Abend Thomas
Pierrot Jean-Michel
Robert Patrice
Atofina
Reddick Judy M.
Smith , Gambrell & Russell, LLP
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