Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-03-27
2002-07-16
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S163000, C521S166000, C521S167000, C521S173000, C521S174000, C521S175000, C521S176000, C528S073000, C528S076000, C528S077000, C528S078000, C528S080000, C528S081000, C528S083000
Reexamination Certificate
active
06420446
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel polyurethane composition and a method of preparing same.
BACKGROUND OF THE INVENTION
Polyurethanes are used in many familiar products, such as elastomers, solid articles, films, and in the manufacturing of foams. The various uses require the polyurethanes to exhibit certain properties such as low temperature flexibility, high tensile strength, high tear strength, high elongation, abrasion resistance, solvent resistance and the like, to ensure that the articles made therefrom can withstand the environments in which they are used. The continuing and, indeed, growing attractiveness of using polyurethanes in various products and uses has prompted the continuing effort to identify polyurethanes exhibiting these properties to a greater degree, and exhibiting optimal combinations of these properties than currently available polyurethanes.
The present invention is directed to such polyurethanes. These are useful in the manufacture of foams, elastomers, solid articles such as shoe soles, and other uses to which polyurethanes are put.
Conventionally, polyurethanes are obtained by reacting a polyester polyol with a diisocyanate whereby the hydroxyl groups on the polyester polyol are endcapped with isocyanate groups, thereby forming a prepolymer. The prepolymer is chain extended by contacting it with a suitable di- or higher-functional chain extender bearing functional groups reactive with the terminal isocyanate groups on the prepolymer.
While some branched polyester polyols have found use in the manufacture of polyurethane, wherein the polyester is derived from a trifunctional or tetrafunctional polyol (such as, respectively, glycerin or pentaerythritol,) the present invention has unexpectedly discovered that polyesters derived from sorbitol provides superior properties compared to conventional polyurethanes.
BRIEF SUMMARY OF THE INVENTION
The polyurethane of the present invention is prepared from a sorbitol-branched polyester. In a particular practice of the invention, sorbitol (or mixtures of sorbitol with other suitable polyols as hereinafter described) is synthetically incorporated into the backbone of a polyester. The sorbitol-branched polyester that results car be employed to fabricate polyurethanes by e.g., reaction with an isocyanacte with chain extension. The polyurethane that eventuates exhibits physical properties superior to those heretofore known, including improved low temperature flexibility, tensile strength, tear strength, modulus strength, elongation %, abrasion resistance, rebound %, solvent resistance etc.
DETAILED DESCRIPTION OF THE INVENTION
The polyurethane of the invention is fabricated using a sorbitol-branched polyester. Without limitation, the sorbitol-branched polyester is formed by reacting sorbitol (or a mixture of sorbitol and other polyols as defined hereinbelow) and a diol with a diacid (or arhydride thereof).
As used herein:
Polyols: polyols useful in the present invention include those containing 2 or more (e.g. 5 to 12) hydroxyl groups and up to 50 carbon atoms. They may be in the D,L, or mixed D,L form. Alkoxylates of such polyols are also within the ambit of the present invention inasmuch as they are hydroxyl terminated. They can be alkoxylated with up to 30 moles (per mole of polyol) of alkylene oxide such as ethylene oxide, propylene oxide, butylene oxide etc. and mixtures thereof. Examples of polyols in this regard include: glcuose, dipentaerythritol, sucrose, tripentaerythritol, allitol, cyclodextrin (cycloheptaamylose), dulcitol (galactiol), glucitol, mannitol, altritol, iditol, ribitol, arabinitol, xylitol, maltitbl, lactitol, trimethylolpropane, glycerin, trimethylolethane, tris-(2-hydroxyethyl) isocyanurate, tris-(2-hydroxypropyl) isocyanurate, tris-(3-hydroxpropyl) isocyanurate triisopropanolamine, and pentaerythritol.
Diols: diols useful in the invention include those containing 2 to 12 carbon atoms. In cases where glycol ethers are utilized in the diol component, it is preferred that they contain from 4 to 12 carbon atoms. Examples of diols include: ethylene glycol, diethylene glycol (which is a preferred diol), 1,3-propylene glycol, 1,2-propylene glycol, 2,2-diethyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 1,2-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylenediol, and 2,2,4,4-tetramethyl-1,3-cyclobutanediol.
Diacids: diacids useful in the present invention include: aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, ethylenically unsaturated alkenyl dicarboxylic acids, or mixtures of two or more of these acids. Preferred are alkyl dicarboxylic diacids which generally will contain 2 to 12 carbon atoms, and aromatic dicarboxylic diacids which generally contain 6 to 12 carbon atoms. Examples of useful diacids include: oxalic, malonic, dimethylmalonic, succinic, glutaric, adipic, trimethyladipic, pimelic, pivalic, dodecanedioc, 2,2-dimethylglutaric, azelaic, sebacic, maleic, fumaric, suberic, 1,3-cyclopentanedicarboxylic, 1,2-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, 1,4-cyclohexanedicarboxylic, phthalic, terephthalic, isophthalic, tetrahydrophthalic, hexahydrophthalic, 2,6-norbornanedicarboxylic, 1,4-naphthalic, diphenic, 4,4′-oxydibenzoic, diglycolic, thiodipropionic, 4,4-sulfonyldibenzoic, and 2,5-naphthalenedicarboxylic acids. Anhydrides of any of the foregoing diacids are also employable.
Preferred diacids include: isophthalic acid, terephthalic acid, phthalic acid, adipic acid, tetrahydrophthalic acid, pivalic acid, dodecanedioic acid, sebacic acid, azelaic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, maleic acid, fumaric acid, succinic acid, 2,6-naphthalenedicarboxylic acid, glutaric acid, and any of the anhydrides thereof.
Formation of the Sorbitol-Branched Polyester:
In the present invention, the total amount sorbitol (or mixtures of sorbitol with other polyols) and diol is sufficient to provide an excess of hydroxyl groups with respect to diacid carboxylic groups (similar considerations apply to the use of anhydrides of said diacids). It will be recognized that to ensure that the sorbitol-branched polyester is capped with terminal hydroxyl groups, it may be necessary to provide in the reaction mixture more than simply a slight stoichiometric excess of the indicated component; the degree of excess is tempered, however, by the effect of excess on the distribution of polymeric chain lengths formed in the condensation polymerization.
Sorbitol is present in the reaction mixture in an amount sufficient to provide a residue in the resultant polyester constituting about 0.1 wt. % to about 15 wt. % of said polyester. In a preferred practice, this percentage is at least about 0.5 wt. %, more preferably at least about 1 wt %, including e.g., about 5% to about 15 wt %.
The reaction mixture containing the sorbitol, diol and diacid (or anhydride) is subjected to condensation polymerization conditions effective to cause the reactants to react with each other to form the sorbitol-branched polyester. In general, effective condensation polymerization conditions are familiar to (or otherwise readily ascertainable by) the practitioner. It is preferred not to carry out the reaction in a solution. However, if a solvent is desired, it should be high boiling (i.e. a boiling point above about 140° C.) Examples of suitable solvents include: DMF (dimethylformamide), DMA (N,N-dimethylacetamide), xylene and DMSO. Combinations of solvents may also be employed.
Preferably, the reaction mixture for carrying out the condensation polymerization includes a small but effective amount (such as up to about 0.02 wt. %) of a catalyst for the polymerization. Useful catalytic compounds include: protonic acids, tin compounds, titanium compounds and antimony compounds.
Typical
CK Witco
Sergent Rabon
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