Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1999-04-07
2001-01-16
Gupta, Yogendra (Department: 1751)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C428S3550RA, C528S328000, C528S342000, C525S419000, C525S420000
Reexamination Certificate
active
06174988
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an adhesive composition which comprises (a) an adhesive carrier, and (b) an adhesively effective amount of a polyamino acid salt selected from the group consisting of polyaspartic acid salts, polyglutamic acid salts, and copolymers of polyaspartic acid salts with polyglutamic acid salts, and mixtures thereof. The present invention also pertains to an article to which the adhesive composition has been applied, a method for adhering a first substrate to a second substrate employing the polyamino acid salts, and to an improved method for making polyamino acid salts.
BACKGROUND OF THE INVENTION
Hot-melt adhesives are nonvolatile thermoplastic polymers that are heated to a melt and then applied as a liquid to a substrate. The adhesive bond forms when the thermoplastic polymer cools and resolidifies. Desirable hot-melt adhesive formulations provide good physical properties over a wide range of temperatures. Compounded thermoplastic polymers include ethylene-vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene-butadiene copolymers, ethylene-ethyl acrylate copolymers, and low density polypropylene. Uncompounded thermoplastic polymers include polyesters, polyamides, and polyurethanes. Conventional additives, such as flexibilizers, plasticizers, tackifying agents, antioxidants, waxes, and fillers, are generally incorporated into the adhesive to improve the mechanical shock resistance and the thermal properties of the adhesive.
Problems with using hot-melt adhesives usually involve poor high temperature performance because thermoplastics tend to creep under load. These problems can be minimized by cross-linking after the adhesive has been applied, but not at the temperature at which the adhesive is kept liquid in the applicator. Adhesives providing high temperature performance tend to be the most brittle while room temperature curing adhesives tend to provide the lowest performance.
Solvent-based adhesives are usually elastomeric materials formed by solution of a high molecular weight polymer in an appropriate solvent. Rubber-based adhesives generally contain an elastomer, such as Neoprene (polychloroprene), to provide most of its strength. Starch adhesives in the form of amylose and amylopectin are often chemically modified such as by treatment with mineral acid to form a thin boiling starch, by treatment with an oxidizing agent to form a starch having reduced chain associations, or by esterification to provide novel starch derivatives. Cellulosic adhesives are obtained by modification of cellulose such as by nitration to provide cellulose nitrate, by esterification to provide esters such as cellulose acetate, by ethoxylation to provide hydroxyethylcellulose, or by etherification to provide ethers such as methylcellulose.
Tackifying resins are useful in modifying many different types of adhesives and include abietic acid and pimaric acid, which are modified by heating to induce disproportionation, by reaction with alcohols to provide esterified products, and by reaction with various catalysts to hydrogenate or polymerize the material; aromatic resins such as coumarone-indene resins; chemicals such as indene or methylindene polymerized with styrene or methylstyrene to provide aromatic tackifying resins; and aliphatic hydrocarbon tackifying resins obtained by polymerizing cis- and trans-1,3-pentadiene, and isoprene and dicylopentadiene.
Protein-based adhesives are derived from blood, fish skin, casein, soybeans, animal hides, bones, and connective tissue. Cross-linking methods include insolubilization by denaturation. A typical formula for a protein-based adhesive includes a natural protein solubilized by reaction with sodium hydroxide, and then dispersed in water. This dispersed protein is then mixed with a defoamer, hydrated lime (cross-linking agent), sodium silicate, various chemical denaturants, and biocides. Depending upon the formulation, the pot life of the adhesive can be from several hours to several days.
While there are many disclosures that describe the preparation of adhesive compositions, none of the disclosures describe methods that are entirely satisfactory for preparing adhesive compositions. None of the disclosures describe the preparation of water-borne adhesive compositions that can be reproducibly prepared and are biodegradable and environmentally friendly. The present invention provides such improved water-soluble, biodegradable, adhesive compositions without the disadvantages characteristic of previously known compositions.
SUMMARY OF THE INVENTION
This invention relates to an article, having applied to a portion thereof, an adhesive composition, wherein the adhesive composition comprises:
(a) an adhesive carrier; and
(b) an adhesively effective amount of a polyamino acid salt selected from the group consisting of polyaspartic acid salts represented by Formula (1):
polyglutamic acid salts represented by Formula (2);
and copolymers of the polyaspartic acid salts represented by Formula (1) with the polyglutamic acid salts represented by Formula (2), and mixtures thereof; wherein
(i) M
+
is selected from the group consisting of a mixture of Ca
2+
and Na
+
cations present in a ratio from about 25:75 to about 95:5, respectively; a mixture of Zn
2+
and Na
+
cations present in a ratio from about 25:75 to about 80:20, respectively; a mixture of Ca
2+
and NH
4
+
cations present in a ratio from about 25:75 to about 95:5, respectively; a mixture of Zn
2+
and NH
4
+
cations present in a ratio from about 25:75 to about 80:20, respectively; monovalent and multivalent organic quatemary ammonium cations; and monofunctional and multifunctional amines;
(ii) the ratio of n
1
to n
2
is from about 1:99 to about 99:1; and
(iii) the molecular weight of the polyamino acid salt is from about 1,000 to about 1,000,000.
This invention also pertains to an adhesive composition which comprises:
(a) an adhesive carrier; and
(b) an adhesively effective amount of a polyamino acid salt selected from the group consisting of polyaspartic acid salts represented by Formula (1):
polyglutamic acid salts represented by Formula (2);
and copolymers of the polyaspartic acid salts represented by Formula (1) with the polyglutamic acid salts represented by Formula (2), and mixtures thereof; wherein
(i) M
+
is selected from the group consisting of a mixture of Ca
2+
and Na
+
cations present in a ratio from about 25:75 to about 95:5, respectively; a mixture of Zn
2+
and Na
+
cations present in a ratio from about 25:75 to about 80:20, respectively; a mixture of Ca
2+
and NH
4
+
cations present in a ratio from about 25:75 to about 95:5, respectively; a mixture of Zn
2+
and NH
4+
cations present in a ratio from about 25:75 to about 80:20, respectively; monovalent and multivalent organic quaternary ammonium cations; and monofunctional and multifunctional amines;
(ii) the ratio of n
1
to n
2
is from about 1:99 to about 99:1; and
(iii) the molecular weight of the polyamino acid salt is from about 1,000 to about 1,000,000.
This invention also pertains to a method for adhering a first substrate to a second substrate which comprises the steps of:
(a) contacting a first substrate with an aqueous solution of a polyamino acid salt;
(b) contacting the first substrate from step (a) with a second substrate;
wherein the polyamino acid salt is selected from the group consisting of polyaspartic acid salts represented by Formula (1):
polyglutamic acid salts represented by Formula (2);
and copolymers of the polyaspartic acid salts represented by Formula (1) with the polyglutamic acid salts represented by Formula (2), and mixtures thereof; wherein
(i) M
+
is selected from the group consisting of a mixture of Ca
2+
and Na
+
cations present in a ratio from about 25:75 to about 95:5, respectively; a mixture of Zn
2+
and Na
+
cations present in a ratio from about 25:75 to about 80:20, respecti
Blumenthal Mitchell
Guth Jacob J.
Iovine Carmine
Lad Niketa S.
Boyer Charles
Gupta Yogendra
Muccino Richard R
National Starch & Chemical Company
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