Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1999-06-29
2001-04-17
Buttner, David J. (Department: 1712)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S307300, C156S327000, C525S539000, C524S376000, C524S377000, C524S378000, C524S457000
Reexamination Certificate
active
06217702
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to resins made from monomers of olefins and carbon monoxide and their use as adhesives.
BACKGROUND
Polymers of carbon monoxide and olefins generally referred to as polyketones are well known in the art. The class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon are of particular interest among polyketone polymers. This class of polymers is disclosed in numerous U.S. patents assigned to Shell Oil Company, exemplified by U.S. Pat. Nos. 4,880,865 and 4,818,811 which are incorporated herein by reference. Polyketone polymers display a well balanced set of mechanical properties which make them particularly useful as engineering thermoplastics.
Other materials having useful properties have also been formed from the combination of various olefins and carbon monoxide. Among these, are relatively low molecular weight materials comprising oligomers or low molecular weight polymers. In this case, however, a monomer other than carbon monoxide and ethene comprises at least 20% wt of the total weight of the polymer. Two olefinic monomers are ordinarily used such as ethene and propene with a relatively high percentage of each (on a weight or molar basis) compared to the linear alternating aliphatic polyketones used as engineering thermoplastics. The monomeric mix will typically include about 50% mole (based on total weight of polymer) CO and about 50% mole of olefins with at least about 30% by weight of the total olefin content comprised of C
3
or higher olefins.
These oligomers or low molecular weight polymers can be employed as thermosets. Depending upon the composition and method of preparation, many will still advantageously exhibit many properties ordinarily associated with thermoplastics under a range of conditions. In such applications they are cured with a curing agent which is generally an amine. Curing may be achieved in the presence of an acid catalyst. Such resins are preferable to existing thermosets in a variety of applications due to reduced environmental nuisances, ease of use, and property mix.
One application of these thermosets is as an adhesive. More particularly, they are useful as glues for wood composites in the preparation of plywood and flake or particle board. To this point, the wood composite industry has generally used adhesives such as urea formaldehyde resins and phenol formaldehyde resins. However, many of the wood composites prepared with them are losing favor in important market segments even though the demand remains generally high for a high impact resistant wood composite with good dimensional stability in the presence of moisture. Much of this is attributable to environmental and safety factors associated with the systems.
Wood glue compositions based on neat olefin/CO resins and amine curing agents have been previously prepared. While these neat glue systems provide good adhesion, their viscosity and pot life are not ideal for many commercial applications. Lowering their viscosity and increasing their pot life would extend the range of applications for which olefin/CO resins could be used. In particular, they could be made much more suitable for use in the production of plywood and oriented strand board under such conditions.
SUMMARY OF THE INVENTION
In one aspect of this invention, olefin/CO copolymers are graft copolymerized with vinyl monomers. The graft copolymers are excellent glues, particularly in wood applications, and are cured by reaction with an amine curing agent in the presence of an acid catalyst. The graft copolymers are advantageously prepared as low molecular weight polymers.
In another aspect of this invention improved adhesives are prepared. These adhesives are particularly useful for binding wood and wood byproducts and are prepared based on a copolymer of carbon monoxide, olefinically unsaturated compounds, and a curing agent.
In another aspect of this invention a wood composite is presented. The composite comprises wood parts adhered to one another by means of a cured binder which is obtainable by curing a curable resin composition which contains a copolymer of carbon monoxide with an olefinically unsaturated compound and a curing agent.
DETAILED DESCRIPTION
Neat olefin/CO copolymer resins in combination with amine curing agents can be effectively used as wood glues. In the practice of this invention olefin/CO resins are improved through graft copolymerization. It has been found that converting the neat olefin/CO copolymer this way makes the system amenable to waterborne application, significantly lengthens potlife, and reduces the viscosity thereby significantly improving the workability of these systems. Furthermore, grafting the olefin/CO copolymers can significantly reduce the overall raw material cost of the glues since a major portion of the glue can be an inexpensive material such as styrene. The graft copolymer is preferably made by imbibing a vinyl monomer into the oil phase of a dispersion of olefin/CO copolymer. Grafting is achieved with the addition of a radical initiator.
Copolymers of carbon monoxide and an olefinically unsaturated compound are known. Preferably the copolymer contains 1,4-dicarbonyl entities in its polymer chain because this arrangement accommodates certain curing reactions as, for example, with poly-primary-amines described more fully below. Such olefin/CO copolymers can be prepared by palladium catalyzed polymerization using the methods known from, for example, EP-A-121965, EP-A-181014 and EP-A-516238 (the disclosures of which are incorporated herein by reference). The polymers so prepared may be linear alternating copolymers of carbon monoxide and the olefinically unsaturated compound(s). That is, the polymer chains contain the monomer units originating in carbon monoxide (i.e., carbonyl groups) and the monomer units originating in the olefinically unsaturated compound(s) in an alternating arrangement. Perfectly alternating copolymers of carbon monoxide and olefinically unsaturated compounds are preferred because these have a higher content of carbonyl groups in the polymer chain relative to random copolymers. This can contribute to the quality of the cure of resins made from these systems leading to a high level of crosslinking.
The copolymers of carbon monoxide and olefinically unsaturated compounds may be based on a hydrocarbon as the olefinically unsaturated compound, but the olefinically unsaturated compound may also contain a heteroatom provided that it is separated from the double bond by a spacer group. For example, comonomers such as 10-undecen-1-ol and 10-undecenoic acid can be used. It is preferred that the copolymer is based on an olefinically unsaturated hydrocarbon having up to 10 carbon atoms. Aliphatic &agr;-olefins with 3 to 6 carbon atoms are particularly suitable in this capacity and include, for example, those having a straight carbon chain such as propene, 1-butene, 1-pentene and 1-hexene. Propene is the preferred monomer of this group. It is most preferred to use a combination of ethene and propene with propene comprising the primary monomer.
The molecular weight of the copolymer prior to grafting may vary between wide limits. Copolymer with a number average molecular weight in the range of from 200 to 20,000 can be used. However, copolymers having number average molecular weights between about 500 to 5000 are preferred. Molecular weights from 1000 to 4000 are most preferred. The copolymers typically have a molecular weight distribution, such that their Q value amounts to 1.1-5, more typically 1.5-3, the Q value being the quotient of the weight average molecular weight and the number average molecular weight. The relatively low molecular weight of the copolymer enables the resin systems of this invention to be used as a liquid at the temperatures generally used in processing and working with the copolymer. This is frequently in the range of 10-80° C., more frequently in the range of 20-60° C. The processing of the copolymer encompasses, for example, the preparation of the bind
Buttner David J.
Shell Oil Company
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