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
2001-02-05
2002-10-15
Sanders, Kriellion A. (Department: 1714)
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...
C524S481000, C524S484000, C524S356000, C524S357000, C524S354000, C524S315000, C524S098000
Reexamination Certificate
active
06465558
ABSTRACT:
FIELD OF INVENTION
The present invention concerns a solvent based adhesive composition for bonding polymer articles together, and more particularly an adhesive composition comprising a solvent system and an adhesive polymer system.
BACKGROUND OF THE INVENTION
Solvent based adhesive compositions are used to adhere one polymer article to another polymer article or to bond polymer articles to other substrates such as wood or metal. These adhesive compositions generally work by providing an adhesive polymer in solution. The adhesive composition is applied to at least one of the polymer articles to be bonded and then the solvent is removed to set the adhesive. Adhesive compositions of this type are believed to work by partially dissolving or swelling the polymer articles and using the dissolved polymer as a seal. They may also work by depositing adhesive materials having surface energies that are matched to the surface energies of the materials being joined.
One of the problems encountered when attempting to bond polymer articles together or to other substrates is the incompatibility of the materials. For instance, it is very difficult to adhere to polymers such as acrylics to polymer such as polyolefins. Due to the low solubility and low surface energy of polyolefins, it is difficult, in general, to obtain good adhesion to polyolefins.
In addition to bonding different polymer articles together, it is often difficult to bond polymer articles to wood or metal substrates. This is especially true for polyolefin films or substrates. Typically films are adhered to wood or metal substrates by heat lamination of the film onto the substrate. However, it is often difficult with polyolefin films to provide the adhesion necessary to prevent delamination.
It is desirable to have a binding composition having a compatible polymer that can provide the adhesion needed to attach the desired polymer articles together. It would be desirable to have an adhesive composition that could bond polymer articles together, and also could bond polymer articles to wood or metal substrates.
SUMMARY OF THE INVENTION
This invention relates to a solvent based adhesive composition comprising a major amount of a solvent system comprising one or more solvents having solubility parameters within the range of from about 7.5 to about 10 (cal/cm
3
)
½
, and a minor amount of an adhesive polymer system comprising one or more adhesive polymers dissolved in the solvent system. In one embodiment, the solvent system comprises the combination of a terpene and an aldehyde, ketone, or an aromatic solvent. The invention also relates to a method of bonding a polymer article to a substrate comprising the steps of providing a polymer article and a substrate, applying a solvent based adhesive composition according to the invention to a portion of the polymer article and/or substrate that are to be adhered together, evaporating at least a portion of the solvent, and pressing the polymer and substrate together at an elevated temperature. The solvent based adhesive composition provides good adhesion between polymer articles, and in particular between acrylic and polyolefin films. The solvent based adhesive composition also provides good adhesion between polymer articles, and in particular polymer films, and metal or wood substrates.
The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed.
DETAILED DESCRIPTION
As described herein, the term “compatible” means that the components used in the adhesive composition remain stable at operating conditions. In one sense, the term “compatible” refers to the ability of the solvent based adhesive composition to form a solution or dispersion which does not form inseparable phases at operating conditions. For instance, at room temperature the components may separate but upon heating mildly to approximately 80-90° F. and mild stirring, the components form a stable dispersion which is useful as a solvent based adhesive composition.
As used in the instant specification and in the appended claims, the term “solubility parameter” and its values are defined in
Polymer Handbook
, Third Edition, J. Brandrup, E. H. Immergut, Editors, 3rd Edition (1989), pgs. 519 et seq., which is hereby incorporated by reference. The
Polymer Handbook
provides a listing of the solubility parameters for many common solvents and polymers, but it may be necessary to calculate the parameters of the solvent using the guidelines set forth in the
Polymer Handbook
or using other scientifically acceptable methods, which are known.
The term adhesive polymer is understood to mean a polymer that provides bonding in the context of the solvent based adhesive composition. An adhesive to polymer must be soluble or dispersible, at least in part, in the solvent system.
As described above, the invention relates to solvent based adhesive composition that comprises a major amount (i.e., more than about 50% by weight) of a solvent system and a minor amount (i.e., less than about 50% by weight) of an adhesive polymer system. The adhesive polymer system or adhesive polymers are sometimes referred to herein as the solids. Typically the solvent based adhesive composition has from about 5 to about 10, or from about 6 to about 9, or from about 7 to about 8 parts of solvent system for each part of solids. Here and elsewhere in the specification and claims, the range and ratio limits may be combined. Each of the components of the adhesive composition is discussed below.
Solvent System
The solvent system comprises one or more solvents having solubility parameters from about 7.5 to about 10, or from about 7.9 to about 9.0, or from about 8.1 to about 8.8 (cal/cm
3
)
½
. The solvents must disperse or dissolve the adhesive polymer system. Solvents that may be used include terpenes, aldehydes, ketones, diacetone alcohol, ethylene glycol ethers, such as diethylene glycol monoethyl ether and ethylene glycol dimethyl or monobutyl ether, alkyl acetates, such as ethyl or butyl acetate, alkyl caprolactams, such as methyl or ethyl caprolactams, and furane.
In one preferred embodiment, the solvent system comprises a combination of a terpene and an aldehyde and/or a ketone or an aromatic solvent. The terpene is generally present in the solvent in an amount from about 2 to about 20, or from about 5 to about 15, or from about 6 to about 12 parts of terpene for every part of aldehyde, or to ketone by weight.
The terpenes include sesquiterpenes and oxidized terpene derivatives thereof. The terpene may be monocyclic, dicyclic or acyclic compounds. Suitable terpenes include, but are not limited to: dipentene, limonene, citral, pinene, carvone, citronellal, myrcene, ocimene, linalool, phellandrene, carvacrol, and thymol. The terms dipentene or limonene include d-limonene, l-limonene and mixtures of the two. Many commercially available terpenes are alcohols derived from terpenes. Sesquiterpenes include, but are not limited to: cadinene, and caryophyllene. In one embodiment, the terpene is limonene. The aldehydes or ketones generally contain from about 2 to about 20, or from about 3 to about 18, or from about 4 to about 10 carbon atoms. The aldehyde or ketone may be aliphatic or cyclic. The aldehydes include butanal, pentaldehyde, hexaldehyde, heptaldehyde, octanal, nonanal, and decaldehyde. The ketone may be linear or cyclic butanone, pentanone, hexanone, heptanone, octanone, nonanone or decanone. In a preferred embodiment, the aldehyde or ketone is a linear or cyclic heptanone or hexanone. For medical application it is preferred that heptanone is used as the aldehyde or ketone.
In another embodiment, one or more of the solvents in the solvent system comprises an aromatic solvent. Suitable aromatic solvents include benzene and substituted benzenes, such as tol
Birch Timothy W.
Chundury Deenadayalu
Kempthorn James T.
Rohn Andrew M.
Scheibelhoffer Anthony S.
Ferro Corporation
Rankin, Hill Porter & Clark LLP
Sanders Kriellion A.
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