CN1155647C - Printable release coatings and stamp constructions - Google Patents

Abstract

Ink-imprintable compositions comprise a reaction product of a mixed emulsion containing a carboxylic acid terminated polydimethylsiloxane, or an isocyanate terminated polydimethylsiloxane, a hydrophilic isocyanate reactive agent, a polyisocyanate, and at least one dihydroxy terminated oligomer. Ink-imprintable stamp constructions also comprise a plurality of contiguous stamps in a roll or stacked sheet configuration without an independent release liner wherein the stamps have a pressure-sensitive adhesive on the back surface of the stamps and the above ink-imprintable release coating on the face surface of the stamps.

Description

Printable release coating and stamp construction

Field of Invention

This invention relates to ink-imprintable or ink-receptive release coating compositions, and to ink-cancellable self-adhesive postage stamps.

Background of the Invention

A postage stamp is a rather complex item. To meet current user needs, it must be constructed with a high-quality printed front material or backing that can accept complex designs. The stamp must also be stable under a wide variety of environmental conditions and provide an ink-cancellable surface on which the cancellation ink dries rapidly. In addition to being cancelable, the stamp should have a means of detecting the stamp so that envelopes with the proper postage can be canceled on a canceling machine. The means for detecting the stamp can be either on the ink-erasable surface or, prior to printing, in the paper used to make the stamp.

Traditionally, postage stamps have been manufactured with water-soluble, water-activated binders. It has been the postal service's desire not only to convert the adhesive into a self-adhesive or pressure sensitive adhesive, but also to provide such stamps in traditional and new formats. A new format offers self-adhesive stamps that can be dispensed from ticket vending machines. An older format provided stamps that were dispensed from a self-retracting tape or roll.

The self-rewinding construction consists of a band which, in the case of postage stamps, provides a number of consecutive stamps marked at regular intervals along its length to indicate where die-cuts are made to separate the stamps. These stamps are coated with a pressure-sensitive adhesive on the back. The reverse or obverse of these stamps must provide an ink-cancellable surface. When the stamp unwinds itself to form a web, the pressure-sensitive adhesive comes into contact with the front side of another stamp. The adhesive sticks to the front side, making it difficult or impossible to unwind the web without damaging the front side or printing surface. It is possible to reduce the adhesive bond strength between the pressure sensitive adhesive and the stamp construction face when in a self-rolling tape or web by applying a release coating on the stamp face Decreases the adhesion of the pressure sensitive adhesive to the front side of the stamp construction.

US Patent 5,082,704 describes a film release sheet for bituminous roofing sheets. The release composition comprises a polydimethylsiloxane diol or triol, an organic isocyanate, an organic polyol, a compound having a hydrophilic center and isocyanate-reactive groups and A chain extender.

US Patent 5,165,976 describes a substrate provided with a release surface by application of an emulsion. The emulsion is a blend of a vinyl addition silicone system, a catalyst for the system, and a particulate component which may be either inorganic or organic in nature but is preferably a resin. Each of the ingredients of the emulsion is itself an emulsion. This vinyl addition silicone system is cured by heating and dehydration. The product can be used in a full range of release applications, especially pressure sensitive adhesive webs, and can be converted at high speeds.

US Patent 5,356,706 describes a modified silicone copolymer that can be used as a release agent. The modified silicone is the reaction product of a di-omega-organofunctional dimethylsiloxane oligomer having terminal active hydrogen groups, a carboxyl-bearing monomer, and a diisocyanate. The copolymer is reported to provide good release properties for sticky adhesive substances.

US Patent 5,478,880 describes a release composition for repositionable adhesives. The release composition is described as a mixture of an ethylene-vinyl chloride copolymer and a polyethylene emulsion.

US Patent 5,492,599 describes a treated, cellulose-based substrate. The substrate is coated with a cationic polymer primer and a release coating having pendant carboxyl or carboxylate moieties.

US Patent 5,496,635 describes a directly printable composition. The composition is a reaction product of a vinyl functional monomer and a chlorinated olefinic resin. The reaction product optionally includes an amide functional monomer and a free radically polymerizable silicone-containing material.

US Patent 5,543,171 describes an aqueous solution of a polyelectrolyte containing dimethylsiloxane. This solution incorporates polydimethylsiloxane blocks, polar groups, and anionic groups, and is reported to provide lubricity, water repellency, and good release to pressure sensitive adhesives.

U.S. Patent 5,547,738 describes the production of linerless label stock in which a single substrate is moved through a coater and a tie coat is applied to the first side of the substrate and a coating to the second side of the substrate. A release coating, and applying a pressure sensitive adhesive to the tie coat.

US Patent 5,663,227 describes a release agent for linerless pressure sensitive postage stamps, preferably an organopolysiloxane polyurea block copolymer containing a dispersion of calcium carbonate and polyvinylpyrrolidone.

European Patent Publication No. 905210 describes the combination of a water-based silicone release emulsion with a water-based polyurethane emulsion to produce a hybrid release emulsion that cures to an unlined release coating that when applied Printable when applied to a substrate such as paper.

Other patents describing release coatings include US Patent Nos. 5,674,626; 5,663,227; 5,621,020; 5,569,515; 5,290,615;

The present invention relates to the provision of ink-imprintable release coating compositions and an ink-moldable fire-sticking surface for use on obverses of pressure sensitive adhesive postage stamp constructions and the like.

Summary of Invention

Ink-imprintable release coating compositions are provided comprising a reaction product of a hybrid emulsion comprising a carboxylic acid-terminated polydimethylsiloxane, a hydrophilic isocyanate-reactive reagent, a polyisocyanate, and at least one dihydroxy-terminated oligomer. Also provided are ink-imprintable stamp constructions comprising a plurality of adjacent stamps in roll or stacked sheet configuration without a separate release liner, wherein the stamp has a pressure sensitive adhesive on the back of the stamp, and There is an imprintable release coating of ink cured as described above on the obverse of the stamp.

In one embodiment, the ink-imprintable release coating composition of the present invention comprises a reaction product of a mixed emulsion containing (A) a polydimethylsiloxane having carboxylic acid terminations ; (B) a hydrophilic isocyanate-reactive reagent; (C) a polyisocyanate; and (D) at least one dihydroxy-terminated oligomer.

In a preferred embodiment, the ink-imprintable release coating composition of the present invention comprises a reaction product comprising a mixed emulsion comprising (A) a carboxylic acid-terminated polydimethylsiloxane (B) a hydrophilic isocyanate-reactive reagent; (C) a polyisocyanate; and (D) at least one dihydroxy-terminated oligomer, wherein the reaction product further contains an ionized Residues of tertiary amines and chain-extending aliphatic diamines.

In another embodiment, the ink-imprintable release coating composition of the present invention comprises a reaction product of a hybrid emulsion containing (A) an isocyanate-terminated polydimethylsiloxane ; (B) a hydrophilic isocyanate-reactive reagent; (C) a polyisocyanate; and (D) at least one dihydroxy-terminated oligomer.

In yet another embodiment, the ink-imprintable release coating composition of the present invention comprises a reaction product of a mixed emulsion containing (A) an isocyanate-terminated polydimethylsiloxane (B) a hydrophilic isocyanate-reactive reagent; (C) a polyisocyanate; and (D) at least one dihydroxy-terminated oligomer, wherein the reaction product further contains an ionized Residues of tertiary amines and chain-extending aliphatic diamines.

In another embodiment, there is provided a release coating for an unlined, pressure sensitive adhesive substrate, the release coating being adapted for print receptivity to permanent inks, the release coating A reaction product comprising a mixed emulsion comprising: (A) at least one of carboxylic acid terminated polydimethylsiloxane or isocyanate terminated polydimethylsiloxane; (B) a hydrophilic isocyanate-reactive agent; (C) a polyisocyanate; and (D) at least one of a diamino-terminated polyether oligomer and a diamino-terminated polyester oligomer.

Detailed description of the invention

Preferably, the silicone component of the ink-imprintable release coating composition of the present invention is a polydimethylsiloxane having carboxylic acid terminations. The polydimethylsiloxane is a condensation cure silicone polymer component. The condensation cure silicone polymer is generally prepared by having a silicone compound containing silanol (Si-OH) groups in a substantial proportion, typically about 10% to about 100%, based on silicon atoms. %Si-H group of siloxane crosslinking agent reaction to prepare. Such compounds include polymeric compounds such as trimethylsilyl-terminated polymethylhydrogensiloxane. The viscosity of the crosslinking agent at 25°C can be up to about 1000 centipoise, preferably in the range of about 25 to about 1000 centipoise.

The reaction of the silicone compound containing silanol (Si-OH) groups with the siloxane crosslinker is carried out in the presence of a catalyst, generally a Group IVA catalyst such as a tin catalyst.

The silicone polymers may be prepared by hydrosilylation using as a catalyst any compound capable of catalyzing the addition of silicon-bonded hydrogen atoms to olefinic double bonds. For example, silicone-soluble complex compounds of Group VIII transition metals, especially platinum, may be used. Examples include a number of noble metals such as rhodium, nickel, palladium, and platinum, and their organometallic complexes, and the catalysts disclosed in US Pat. Nos. 4,256,870 and 4,340,647. These materials include, for example, finely divided platinum catalysts (US Patent 2,970,150), chloroplatinic acid catalysts (US Patent 2,823,218), platinum-hydrocarbon complexes (US Patents 3,159,601; 3,159,662), platinum Patent 3,416,946), platinum-alkyne complex (US Patent 4,603,215), reaction product of chloroplatinic acid and tetravinylcyclotetrasiloxane in ethanol solution in the presence of sodium bicarbonate (US Patent 3,715,334), from Complexes prepared from chloroplatinic acid and containing unsaturated organosilicon compounds (US Patent 3,419,593) by reaction between a silicon hydride or siloxane hydride and a platinum(O) or platinum(II) complex Catalysts provided (US Patent 4,705,765). Platinum compounds are generally preferred, although compounds of ruthenium, rhodium, palladium, osmium and iridium may also be used. A better _catalyst in terms of reactivity and cost is chloroplatinic acid ( _H2PtCl6-6H2O ) _. Catalyst concentrations of 0.0005 to about 0.5% by weight, based on the weight of the silicone mixture, result in substantially complete polymerization. Other platinum compounds may also be used to advantage in some cases, such as _PtCl2 , platinum dibenzonitrile dichloride, and platinum divinyl and cyclovinyl complexes. Platinum on carbon is also effective for conducting high temperature polymerizations.

For coating compositions, catalyst amounts range from about 10 to about 500 ppm depending on factors such as reaction rate and cost. The mixture of reactants is generally prepared as an emulsion, and the emulsion may also include other materials such as stabilizers, fast cure additives, solvents, anchoring agents and/or antiblocking agents.

The carboxylic acid terminated polydimethylsiloxane utilized in the release coating composition of the present invention can be prepared by reacting a dihydroxy terminated polydimethylsiloxane with a cyclic anhydride. The dihydroxy-terminated polydimethylsiloxane can be conveniently prepared by reacting a SiH-terminated polydimethylsiloxane with, for example, an alkylene oxide or allyl alcohol/alkylene oxide condensate to prepare. Polydiorganosiloxanes with SiH end groups can be prepared from silicone compounds containing silanol groups which can be represented by the formula

In the formula, each R ₀ is independently a monovalent hydrocarbon group without aliphatic unsaturation, such as methyl, ethyl, propyl, butyl, etc., and a>0. The molecular weight of these polysiloxanes can range from about 2000 to about 20,000, and the viscosity at 25°C can range from about 25 to about 1000 centipoise. A preferred silanol polysiloxane is a silanol terminated linear polydimethylsiloxane fluid having a viscosity of from about 300 to about 1000 cps.

Particularly useful as a crosslinking agent for condensation-curable silicones is one having from about 10% to about 100% Si-H containing siloxy groups and having a viscosity at 25°C in the range of from about 25 to about 1000 centipoise. , Trimethyl chain-terminated polymethylhydrogensiloxane.

The curing reaction that occurs between the silanol-functional polysiloxane and the silicone crosslinker is a condensation curing reaction. The composition can be thermally cured by a catalyzed crosslinking reaction between the pendant hydroxyl groups of the silanol chain-terminated dialkylsiloxane polymer and the Si-H groups of the silicone crosslinking compound.

In one embodiment, a polyethylene oxide/polypropylene oxide block can be inserted between the siloxane block and the carboxylic acid terminated moiety via a ring opening reaction product. The chain length of this block is preferably from 2 to about 100 oxyalkylene units.

Alternatively, the silicone component of the ink-imprintable release coating composition of the present invention may be an isocyanate-terminated polydimethylsiloxane. The isocyanate-terminated polydimethylsiloxane can be a polyisocyanate and a polydimethylsiloxane with at least one of functional groups -CO ₂ H, -OH, -NHR, -NH ₂ and thiol Siloxane reaction product.

The hydrophilic isocyanate-reactive component of the ink-imprintable release coating composition of the present invention may be a linear or branched aliphatic monomer containing two primary hydroxyl groups and one tertiary carboxylic acid group. The hydrophilic isocyanate-reactive component of the ink-imprintable release coating composition of the present invention may also be a linear or branched aliphatic monomer containing two primary hydroxyl groups and one tertiary sulfonic acid group. The hydrophilic isocyanate-reactive component may contain from about 2 to about 20 carbon atoms.

The polyisocyanate component of the ink-imprintable release coating composition of the present invention may be an organic diisocyanate. Any of the diisocyanates used to form polyurethanes are suitable for use in the present invention. Preferably, the isocyanate is a diisocyanate which may include aliphatic diisocyanate, aromatic diisocyanate, cycloaliphatic diisocyanate and the like. Mixtures of one or more diisocyanates may be used. Examples of useful diisocyanates include, but are not limited to, toluene-2,4-diisocyanate, mixtures of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate, m-phenylene diisocyanate, methylene diphenyl isocyanate (MDI), hydrogenated MDI, isophorone diisocyanate and hexamethylene diisocyanate. The isocyanate component can also be a blocked isocyanate.

The polyisocyanate component of the ink-imprintable release coating composition of the present invention may also be a blocked isocyanate, wherein the free isocyanate is generated by heating. Such blocked isocyanates are also known as shunts, disguised isocyanates, or blocked isocyanates, see e.g. J.H. Saunders and K.C. Frisch, "Polyurethanes: Chemistry and Technology", pp. 118-121 , Interscience PL blishers, 1962. These are systems that are stable at room temperature but react at elevated temperatures as in the presence of isocyanates. Blocked isocyanates are reaction products of isocyanates with certain active hydrogen compounds such that the addition products have only limited thermal stability. A typical example is the reaction product of an isocyanate with a phenol, which is stable at room temperature but dissociates at temperatures in the range of 150-200°C to regenerate the isocyanate. Active hydrogen compounds useful in making such blocked isocyanates include phenol, m-cresol, diethyl malonate, ethyl acetoacetate, ethyl cyanoacetate, alpha-pyrrolidone, and epsilon-caprolactam. By way of example and not limitation, the polyisocyanate may be a heated reaction product of a phenol ketone oxime. The blocked polyisocyanate may further be a reaction product of a phenol ketoxime, polyisocyanate, and caprolactam.

Preferred tertiary amine components of the ink-imprintable release coating compositions of the present invention include, but are not limited to, trialkylamines, such as triethylamine or tributylamine, pyridine, and N,N-dimethylethanolamine.

The diamine component of the ink embossable release coating composition of the present invention can be selected from the group consisting of: hydrazine, isophorone diamine, α, ω-diaminopolyether, aminoethylpiperazine, piperazine , (polymethylene) diamine, xylylene diamine and others.

According to the present invention, dihydroxy-terminated oligomers include at least one of the following functionalities: ester, ether, olefin, alkylene, and the like. In one embodiment, the polyether or polyester oligomer having dihydroxyl terminations according to the invention is preferably selected from the group consisting of: polyethylene oxide, polyethylene glycol, polypropylene oxide, polypropylene glycol, hydroxyl terminated Polycaprolactone polymers, hydroxyl-terminated polyesters, etc.

In another embodiment, additionally at least one diamino-terminated oligomer containing at least one of the above-identified functionalities may also be included in the reaction product, or may replace the dihydroxy-terminated oligomer. oligomers. The dihydroxy-terminated and/or diamino-terminated oligomer component of the ink imprintable release coating composition of the present invention preferably contains at least one additional functional group selected from the group consisting of: alcohol, amine , carboxylic acids, carboxylates, amides, anhydrides, imides, thiols, phosphoric acids, phosphates, sulfonic acids, sulfonates, and sulfates.

Preferably, the oligomer component is characterized by a number average molecular weight greater than about 100. The molecular weight can be a calculated molecular weight or a number average molecular weight determined by end group analysis.

The release coatings of the present invention can be classified as imidate polymers containing silicone blocks. The silicone blocks are chemically bonded to the imidate polymer chains and are an integral part of the polymer. These modified imidate copolymers can be synthesized by a dimethicone oligomer having dicarboxylic acid terminations, a hydrophilic isocyanate reactive agent, a diisocyanate, dihydroxy terminated oligomers It is obtained by reacting at least one of polyether oligomers having dihydroxyl terminations and/or polyester oligomers having dihydroxyl terminations, for example. More specifically, the modified imidate copolymer is obtained by further reacting the above mixture with an ionized tertiary amine and chain extending with an aliphatic diamine. The term hydrophilic isocyanate-reactive reagent is meant to include hydrogen-containing groups that readily react with isocyanates, and examples of such groups include -OH, -SH, and _-NH2R .

The reaction sequence can be illustrated as follows:

HOOC(PDMS)-COOH+HO-R'(COOH)-OH+OCN-R-NCO

  +HO-(PEO)-OH+HO-(polyester)-OH

↓Heat, solvent (NMP)

↓H ₂ NR-NH ₂ , H ₂ O

↓R″ _NH2

        Silicone Polyurethane (SPU) Emulsion

In the formula, R, R' and R'' are hydrocarbylene groups, and R" is a hydrocarbyl group.

The dimethylsiloxane has carboxylic acid functional groups at each end of the molecule. The second component of the reaction product of the present invention comprising an ink-imprintable release coating is a carboxyl functional organic monomer having two active hydrogens. Alternatively, another ingredient may be included, namely a sulfonic acid functional organic monomer having two active hydrogens. The third component is a difunctional organic compound (eg, diisocyanate) having isocyanate groups at each end that are reactive with the active hydrogen groups of the remaining reactants. The fourth component is at least one of a dihydroxy-terminated polyether oligomer and a dihydroxy-terminated polyester oligomer.

The dimethylorganosiloxane oligomers used to prepare the polysiloxane-urethane release polymers of the present invention are well known materials. Hydroxyl terminated oligomers can be prepared by reacting a linear polydimethylsiloxane oligomer with SiH terminated groups such as an alkylene oxide or an allyl alcohol/alkylene oxide condensate. Easy to prepare. A carboxylic acid-terminated oligomer can be obtained by reacting the hydroxyl-terminated oligomer with a cyclic anhydride.

The dimethylsiloxane oligomers with dicarboxylic acid ends that can be used as reactants during the preparation of the modified silicone polymer can be represented by the following formula

XR-(Si(CH ₃ ) ₂ O) _n -Si(CH ₃ ) ₂ X where n is about 2 to about 200, preferably about 5 to about 100, R is a divalent aliphatic hydrocarbon group, X is a carboxylic acid group.

A hydrophilic isocyanate-reactive reagent can be represented by the formula

XR ¹ (X)(-COOH) _m

In the formula, X is a hydroxyl group, R ¹ is a trivalent or tetravalent group, and m is 1 or 2. Examples of such carboxylic acids include 2,2'-di(hydroxymethyl)propionic acid, tartaric acid, and the like.

The preparation of the polysiloxane-urethane copolymers is generally carried out in several steps. In the first step, a dimethylsiloxane oligomer with a carboxylic acid end, a hydrophilic agent containing two hydroxyl groups and a carboxyl group, a dihydroxy A polyether oligomer, a dihydroxy-terminated polyester oligomer, and an excess of a diisocyanate are reacted to form an isocyanate-terminated prepolymer. The reaction can be carried out neat or in the presence of a solvent to reduce the viscosity. Heat or a catalyst can be used to accelerate the reaction, although mild reaction conditions, generally below 100°C, are preferred in order to avoid reaction of the carboxyl groups with the NCO groups. Suitable solvents include liquids that do not contain any active hydrogen reactive with the diisocyanate, and examples of such solvents include N-methylpyrrolidone (NMP), N,N-dimethylformamide, acetone, dioxane wait.

The amount of organic diisocyanate used in this reaction depends on the number of active hydrogen groups in the reactive mixture, the particular diisocyanate compound used, the molecular weight of the diisocyanate, the NCO/OH ratio, and the like. Using these factors, the exact amount of diisocyanate to use can be readily determined. The initial stoichiometric ratio of NCO to total OH is generally between about 1.3 and about 2.5, usually between about 1.4 and about 2.

Catalysts commonly used to accelerate the NCO reaction can be employed in this reaction, if desired. The use of catalysts is especially useful to accelerate the reaction of aliphatic isocyanates. These catalysts include tertiary amines such as triethylamine, tributylamine, pyridine, and organometallic compounds such as stannous octoate, dibutyltin dilaurate, zinc octoate, and cobalt naphthenate.

Then, the NCO-terminated prepolymer thus prepared is further reacted with an aliphatic diamine to form a copolymer. This reaction is called chain growth. Adjust the total NCO/total active hydrogen ratio to about 1:1. The tertiary amine interacts with the carboxyl groups of the prepolymer and ionizes the prepolymer into an emulsion in water. The ionized prepolymer is then further reacted with a diamine chain extender to increase the molecular weight of the polymer. Typical diamines for chain extension include, but are not limited to, isophoronediamine, omega-amino polyether, aminoethylpiperazine, (polymethylene)diamine, xylylenediamine, and the like.

The ink-imprintable release coating compositions of the present invention may also include inorganic particulates such as silicates such as silica, zinc orthosilicate (marker), clay, calcium carbonate, alumina, zinc oxide, tin oxide, titanium dioxide, other Metal oxides, and mixtures thereof. These inorganic fine particles can be used as solid powder or in colloidal form. These inorganic particles are effective in improving the ink-non-printable characteristics of the release coating, and may also be included in the coating composition to enable automatic positioning of postage stamps on envelopes for cancellation purposes.

Ideally, the hybrid emulsion has a suitable pH for application and is free of agents that would inhibit the cure or rate of cure of the system. A suitable pH is about 8 or below, typically about 4 to about 7. The solids content of the emulsion can be as low as 5% to 10% by weight and as high as 90% by weight. The solids content of the emulsion is preferably from about 25% to about 35% by weight. Solids content can be optimized to facilitate coating, drying and curing processes. On a dry weight basis, coating levels range from about 1 to about 10 g/ ^m2 .

The ink-imprintable release coating composition of the present invention which has been described above can be used to produce conventional pressure sensitive labels, pressure sensitive tapes, and linerless pressure sensitive products such as postage stamps, heat transfer linerless labels, direct thermal linerless labels , and gift wrap materials, all in roll or sheet form.

The ink-imprintable release coating compositions of the present invention which have been described above are particularly useful in the preparation of ink-imprintable postage stamp constructions, more particularly in the preparation of self-rolling postage stamps and stackable sheets (or sheetlets) The stamps are constructed without a separate release liner to prevent these stamps from sticking together. In one embodiment, an ink-imprintable stamp construction will typically consist of a number of consecutive stamps that will self-wind into a web configuration without the use of a separate release liner, and that will have a pressure-sensitive stamp on the back of the stamp. The adhesive and the stamp obverse have an ink embossable release coating cured as described above. The stamps are held in web configuration by the cooperation of the pressure sensitive adhesive and release coating. The ink-imprintable release coating is ink-erasable and enables easy separation of a stamp from the web without damaging the paper stock or printing surface of the stamp.

More significantly, the release coating provides an ink-imprintable release of the pressure sensitive adhesive employed in the postage stamp construction. The bond between the release coating and the stamp obverse is greater than the force required to separate the pressure sensitive adhesive from the release coating when the stamp construction is unrolled.

In one embodiment, an ink-imprintable stamp construction according to the present invention comprises a plurality of continuous stamps in a roll or stacked sheet configuration without a separate release liner, wherein the stamps have an embossed stamp on the back of the stamp. Adhesive sensitive with cured ink imprintable release coating on stamp obverse, said release coating comprising a reaction product of a mixed emulsion containing a carboxylic acid terminated polydimethyl Siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, a dihydroxy-terminated oligomer such as a dihydroxy-terminated polyether oligomer and/or a dihydroxy-terminated oligomer At least one of a terminated polyester oligomer (or alternatively, a diamino terminated polyether oligomer and/or polyester oligomer). The release coating may also contain inorganic particles.

In another embodiment, an ink-imprintable postage stamp construction according to the present invention comprises a plurality of consecutive stamps in a roll or stacked sheet configuration without a separate release liner, wherein the postage stamp has a Pressure sensitive adhesive with cured ink imprintable release coating on stamp obverse, said release coating comprising a reaction product of a mixed emulsion containing a carboxylic acid terminated polydimethylformaldehyde siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, a dihydroxy-terminated oligomer such as a dihydroxy-terminated polyether oligomer and/or a dihydroxy-terminated oligomer At least one of a hydroxyl-terminated polyester oligomer (or alternatively, a diamino-terminated polyether oligomer and/or polyester oligomer), the reaction product further comprising an ion tertiary amines and chain-extending aliphatic diamines.

In another embodiment, the ink-imprintable stamp construction of the present invention comprises a plurality of consecutive stamps in a web configuration, wherein each stamp comprises

(A) a layer of ink-imprintable material having a front side and a back side;

(B) An ink embossable release coating bonded to the front side of the material, said release coating comprising the reaction product of a mixed emulsion containing a polydimethylsiloxane with carboxylic acid terminations Siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, dihydroxy-terminated oligomers such as dihydroxy-terminated polyether oligomers and/or dihydroxy-terminated polyester oligomers (or alternatively, a diamino-terminated polyether oligomer and/or polyester oligomer) at least one; and

(C) a layer of pressure-sensitive adhesive bonded to the back of the layer of ink-imprintable material, whereby the stamp construction maintains a curled configuration under the synergy of the pressure-sensitive adhesive layer and release coating type, and the adhesion between the release coating and the face of the material layer is greater than the force required to separate the release coating from the pressure sensitive adhesive when the stamp construction is unrolled.

In yet another embodiment, the ink-imprintable stamp construction of the present invention comprises a plurality of consecutive stamps in a web configuration, wherein each stamp comprises

(A) a layer of ink-imprintable material having a front side and a back side;

(B) An ink embossable release coating bonded to the front side of the material, said release coating comprising the reaction product of a mixed emulsion containing a polydimethylsiloxane with carboxylic acid terminations Siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, dihydroxy-terminated oligomers such as dihydroxy-terminated polyether oligomers and/or dihydroxy-terminated polyester oligomers (or alternatively, a diamino-terminated polyether oligomer and/or polyester oligomer), said reaction product further comprising an ionized tertiary amine and chain-extending fatty diamines; and

(C) a layer of pressure-sensitive adhesive bonded to the back of the layer of ink-imprintable material, whereby the stamp construction maintains a curled configuration under the synergy of the pressure-sensitive adhesive layer and release coating type, and the adhesion between the release coating and the face of the material layer is greater than the force required to separate the release coating from the pressure sensitive adhesive when the stamp construction is unrolled.

In a preferred embodiment, the ink-imprintable stamp construction of the present invention comprises a plurality of consecutive stamps in a web configuration, wherein each stamp comprises

(A) a layer of ink-embossable paper having a front and a back;

(B) An ink embossable release coating bonded to the front side of the paper, said release coating comprising the reaction product of a mixed emulsion containing a polydimethylsiloxane with carboxylic acid terminations Siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, dihydroxy-terminated oligomers such as dihydroxy-terminated polyether oligomers and/or dihydroxy-terminated polyester oligomers (or alternatively, a diamino-terminated polyether oligomer and/or polyester oligomer) at least one; and

(C) a layer of pressure-sensitive adhesive bonded to the back of the ink-imprintable paper layer so that the stamp construction maintains a curled configuration under the synergy of the pressure-sensitive adhesive layer and release coating type, and the adhesion between the release coating and the face of the material layer is greater than the force required to separate the release coating from the pressure sensitive adhesive when the stamp construction is unrolled.

In another preferred embodiment, the ink-imprintable stamp construction of the present invention comprises a plurality of consecutive stamps in a web configuration, wherein each stamp comprises

(A) a layer of ink-embossable paper having a front and a back;

(B) An ink embossable release coating bonded to the front side of the paper, said release coating comprising the reaction product of a mixed emulsion containing a polydimethylsiloxane with carboxylic acid terminations Siloxane, a hydrophilic isocyanate-reactive agent, a polyisocyanate, dihydroxy-terminated oligomers such as dihydroxy-terminated polyether oligomers and/or dihydroxy-terminated polyester oligomers (or alternatively, a diamino-terminated polyether oligomer and/or polyester oligomer), said reaction product further comprising an ionized tertiary amine and chain-extending Aliphatic diamines; and

(C) a layer of pressure-sensitive adhesive bonded to the back of the ink-imprintable paper layer so that the stamp construction maintains a curled configuration under the synergy of the pressure-sensitive adhesive layer and release coating type, and the adhesion between the release coating and the face of the material layer is greater than the force required to separate the release coating from the pressure sensitive adhesive when the stamp construction is unrolled.

In accordance with the present invention, the ink-imprintable stamp constructions described above containing preferably a carboxylic acid terminated polydimethylsiloxane may alternatively contain an isocyanate terminated polydimethylsiloxane.

The thickness of the layer of ink-imprintable material (eg, paper) can range from about 50 to about 150 μm, but for postage stamp applications is about 80 to about 100 μm. The thickness of the release coating generally ranges from about 0.5 to about 10 μm, more typically from about 1 to about 5 μm. The thickness of the pressure sensitive adhesive layer generally ranges from about 15 to about 30 μm, more typically from about 20 to about 25 μm.

Ink-imprintable release coatings are generally derived from water-based emulsions, and the release force or release at various peel speeds can be determined by the nature of the components of the release coating, the proportions of the components and the coating. layer weight to control.

In the production of the release coating on postage stamps of the present invention, a polydimethylsiloxane with carboxylic acid termination (or alternatively, a polydimethylsiloxane with isocyanate termination), a hydrophilic isocyanate-reactive reagents, a polyisocyanate, a dihydroxy-terminated polyether oligomer, and/or a dihydroxy-terminated polyester oligomer (or alternatively, a diamino-terminated polyether oligomers and/or polyester oligomers) to form a reaction product that is ionized with a tertiary amine and chain-extended with an aliphatic diamine to obtain a coating-suitable Lotion mixture. The emulsion desirably has a pH below about 8. The emulsion is applied to the front side of the stamp or ink-imprintable material by any technique known in the art, typically by heating to dry the coating to remove moisture and cure. This provides a release surface which is clear and strong and which remains substantially on the front side of the substrate, generally the front side of the ink-imprintable material used to form postage stamps.

The layer of ink-imprintable material coated with the silicone release coating composition of the present invention may be of any suitable material which has an affinity for ink to enable printing of graphics of a quality such as those employed in postage stamp construction. Generally, the material is a printable paper and the following is a non-exclusive list of products suitable for use as postage stamp grade paper:

(1) Postage stamp paper, available from P.H. Glatfelter Company (Spring Grove, PA), 65 lbs., 0.0034 inches thick.

(2) Dunn No.55 Spectral Coated No.019 Stamp Grade Paper, available from James River Company (James River, VA).

(3) No. LP-57 postage stamp grade paper, available from American Paper Company (New York, NY).

(4) No. LP-57 postage stamp grade paper, available from Champion International, Inc. (Stanford, CT).

(5) White Coated Stamp Paper No. LP-57 with Barrier Coating, available from Henry & Leigh Slater Ltd. (Bollington-Macceisfield-Chesire, England).

The pressure sensitive adhesives employed in the construction of the postage stamps of the present invention are of the nature that they provide sufficient tack at the expected use temperatures. Such an adhesive would allow initial repositionable bonding to a wide variety of paper substrates (envelopes) over the expected temperature range of use, with a bond strength that increases over time to achieve The permanent bond at the level of the stamp cannot be removed from the paper substrate by tearing the paper.

The amount of pressure-sensitive adhesive employed in the construction of the stamps of the present invention may range from about 1 to about 100 g/m ² , more often the amount is about 15 to about 45 g/m ² , preferably 15 to about 30 g/m 2 . within the range of ^m2 . A wide variety of pressure sensitive adhesives can be utilized including hot melt adhesives, water based adhesives such as water soluble or water dispersible adhesives, and solvent based or organic soluble adhesives. Such adhesive compositions are described in detail in, for example, "Adhesion and Bonding" Encyclopedia of Polymer Science and Engineering, Vol. 1, pp 476-546, Interscience Publishers, 2nd Ed., 1985. Such compositions generally contain an adhesive polymer such as natural, recycled or styrene-butadiene rubber, styrene-butadiene or styrene-isoprene block copolymers, polyisobutylene, poly( Vinyl ether) or polyacrylate as the main component. Other materials may be included in the pressure sensitive adhesive composition, for example, resin tackifiers including such as rosin resin, oil soluble phenolic plastics, or polyterpenes; antioxidants; plasticizers such as mineral oil or liquid polyisobutylene ; and fillers such as zinc oxide or hydrated alumina.

The pressure sensitive adhesive useful in the present invention can be a hot melt material, either rubber-based or acrylic-based. Examples of hot melt adhesives include styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers, these can be combined with hydrocarbon resins or resin esters as described in Korpman U.S. Patent 4,080,348 as disclosed. Other patents describing hot melt adhesives include US Patents 3,676,202, 3,723,170 and 3,787,531.

Useful acrylic pressure sensitive adhesives are typically copolymers prepared by bulk polymerization in the presence of chain terminators. Examples of monomers that can be used to create pressure sensitive acrylic adhesives include, but are not limited to, acrylic acid, methacrylic acid, 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate Esters etc.

The pressure sensitive adhesive preferably has a "G'" dynamic storage shear modulus, measured using a Rheometrics RDS-7700 at 23°C at a deformation rate of 10 ^-7 rad/s, greater than about 10,000 dynes/cm ² , and preferably Is an emulsion acrylic polymer. Specific examples of useful pressure-sensitive adhesives include acrylic-based emulsions such as S-490 adhesive (available from Fasson Company, Pinesville, Ohio); hot-melt tackified Kraton-based adhesives (styrene - Isoprene-styrene block copolymer, also available from Fasson under the name S-246 Adhesive); hot melt tackified pressure sensitive adhesive (also available under the name S-2176 Adhesive available under the Fasson Company); and is also available from the Fasson Company under the name P-5001 Adhesive.

A list of features of one specific example of an acrylic pressure sensitive adhesive useful in the present invention is set forth in Table I below.

Table I

Glass transition temperature (T _g ), °C -38 William Plasticity (WPI), mm 3.42 minimum application temperature °F 10 ℃ -12 Adhesive coating weight (g/m ² ) twenty four 10 minutes 90° peel (pli) initial 1.3 Cleaning/tearing 6 weeks at room temperature 1.5 cleaning/brushing 6 weeks at 70°C 1.7 tear Loop Viscosity (pli) initial 1.8 cleaning 6 weeks at room temperature 2.4 cleaning 6 weeks at 70°C 2.3 cleaning Relocatability initial/6 weeks room temperature ^TYVEK® 30 seconds A/A 60 seconds A/A 90 seconds A/A 1 hour A/F Woven fabric 30 seconds D/D 60 seconds NA 90 seconds NA 1 hour NA Adhesive layer 30 seconds D/D 60 seconds NA 90 seconds NA 1 hour NA 1 hour durability ^TYVEK® initial f 6 weeks at room temperature f Woven fabric initial D. 6 weeks at room temperature D/F Adhesive layer initial f 6 weeks at room temperature D/F

Relocation and Durability Term Codes:

A＝clean E＝sticky on the front

B = substrate (envelope) slightly sticking F = front tear

C = Substrate sticking G = Speckled adhesive transfer

D = Substrate tearing NA = Not applicable

The stamp constructions of the present invention may comprise stacked or block sheet constructions without a separate release liner separating the individual sheets. The presence of the ink-imprintable release coating prevents unwanted adhesion between the pressure sensitive adhesive of one sheet and a second sheet.

One of the advantages of the postage stamp construction of the present invention is that sheets comprising a plurality of postage stamps can be stacked together on top of each other without the need for a release liner between the sheets. Stacks of sheets (sometimes referred to as squares of sheets) that may be prepared in accordance with the present invention may be vertical stacks with straight sides. Although the stack maintains its integrity due to the interaction between the pressure sensitive adhesive layer of the adjacent sheets and the release coating, the sheets can be easily separated due to the presence of the release coating. The stacks of sheets that can be produced according to the invention can also be vertical stacks, in which each sheet is offset from the sheet below it by a short lateral distance.

Self-rolling roll stamp constructions may contain a roll of stamps separated by lines or marks marking where the paper cuts are between each stamp. Each postage stamp consists of an ink-imprintable or ink-blockable fire-adhesive coating on one surface (obverse) of a layer of printable material, such as paper, and is provided with a pressure-sensitive adhesive on the reverse agent. The release coating further provides some means of detecting the position of the stamp on the envelope in an automatic cancellation machine where the top coat contains detectable particles such as zinc orthosilicate. Alternatively, the detectable particles may be coated onto the printable material prior to printing and prior to applying a release coating to the material.

The postage stamp constructions of the present invention can be made by forming a laminate comprising (a) a layer of ink-imprintable paper, (b) a release coating on the face of the paper, and (c) the paper Pressure sensitive adhesive on the back of the ply. The front side of the paper is pre-printed with stamp graphics, and the reverse side can also be printed if desired. Water-based inks can be used. The assembly is then cut and rolled into rolls or cut into sheets of the desired stamp denomination.

As explained above, the ink-imprintable silicone release surface must enable stamps to be peeled (released) from the adhesive surface with sufficiently low force when in roll or stacked sheet form without damaging The printing surface or paper backing, in turn, provides sufficient adhesion to the pressure sensitive adhesive to prevent premature dispensing of the stamps when the web is unrolled. The release force is generally defined as the force required to peel the pressure sensitive adhesive from the release coated surface at a specified speed and angle. The release force is measured by a "90 degree peel adhesion test" (TLM1 Test No. VII, LD. 4-68, PSTC-2, 5th edition). This test measures the peel force required to remove a pressure sensitive adhesive from a substrate when the peel load is applied in a direction perpendicular to the applied adhesive.

In the ratio test, a bead of pressure-sensitive adhesive is pressed onto a surface with a release coating and, after aging, is measured when the bead of adhesive is peeled at a 90-degree angle at a speed of 300 in/min. Anti-adhesive. The apparatus used was a Release and Adhesion Tester available from Testing Machines, Inc. under the designation TMI Model No. 80-14-00. Block release is expressed in grams per inch of width. Three strips of adhesive tape were peeled from each substrate and the values obtained were averaged.

The following examples illustrate the preparation of release coating emulsions according to the invention. In the following examples, the ingredients are identified as follows:

name describe supplier Q2-5187 Hydroxyl-terminated polymer containing 60% polydimethylsiloxane blocks and 40% polyethylene oxide blocks Dow Corning (Midland, Missouri) Q4-3667 Hydroxy-terminated polymer with 40% polydimethylsiloxane blocks and 60% polyethylene oxide blocks Dow Coming Company (Midland, Missouri) ^DESMODUR® W Bis(4-isocyanatocyclohexyl)methane hydrogenated MDI, HMDI Bayer Corporation (Pittsburgh, Pennsylvania) DMPA Di(hydroxymethyl)propionic acid Aldrich Chemical Company F11-56 FOMREZ® 11-56 has a hydroxyl end Witco Corporation (Connie) NMP N-Methylpyrrolidone Aldrich Chemical Company SA Succinic anhydride Aldrich Chemical Company DMEA N,N-Dimethylaminoethanol Aldrich Chemical Company EDA Ethylenediamine Aldrich Chemical Company TEA Triethylamine Aldrich Chemical Company THA tetrahydrophthalic anhydride Aldrich Chemical Company

Example 1

A jacketed reactor equipped with a pitched blade stir bar was maintained at 80°C and the following ingredients were added: 46.25 g (0.025 mole) Q2-5178, 9.57 g N-methylpyrrolidone and 5.00 g (0.05 mole) succinic anhydride. After a reaction time of 2 hours, 4.02 g (0.03 mol) of bis(hydroxymethyl)propionic acid and 24.00 g (0.012 mol) ^of FOMREZ® 11-56 were added. After one hour, 25.22 g (0.097 mol) of ^DESMODUR® W were added, followed by a further 3 hours of reaction. The system was cooled to 35°C and ionized by adding a mixture of 0.07 g N-methylpyrrolidone, 2.67 g (0.03 mole) dimethylethanolamine and 15.00 g deionized water. After 3 minutes of mixing, 60 g of water were added. After an additional 5 minutes of mixing, the chain extender solution, 4.50 g of 33% ethylenediamine and 60 g of water, was added. After mixing for an additional 5 minutes, 185.91 g of water was added to adjust the solids content to 30% solids.

The theoretical parameters of the product are as follows:

Solid (g) 105.99

PDMS (% solids) 17.45

NCO (unreacted) 0.0050

NMP (% product) 3

Amine (% product) 0.76

Acid (% solids) 3.79

HMDI (% solids) 23.79

Esters (% solids) 22.64

Ether (% solids) 26.18

Example 2

A jacketed reactor equipped with a pitched blade stir bar was maintained at 80°C and the following ingredients were added: 33.90 g (0.015 mole) Q4-3667, 4.00 g N-methylpyrrolidone and 3.00 g (0.03 mole) succinic anhydride. After a reaction time of 2 hours, 3.35 g (0.025 mol) of bis(hydroxymethyl)propionic acid and 22.00 g (0.011 mol) of FOMREZ® 11-56 were added. After 1 hour, 20.54 g (0.079 mol) of ^{DESMODUR® W} were added, and then React for another 3 hours. The system was cooled to 35°C and ionized by adding a mixture of 3.66 g N-methylpyrrolidone, 2.225 g (0.03 mole) dimethylethanolamine and 15.00 g deionized water. After 3 minutes of mixing, 60 g of water were added. After an additional 5 minutes of mixing, the chain extender solution, 4.50 g of 33% ethylenediamine and 140 g of water, was added. After an additional 5 minutes of mixing, 62.57 g of water was added to adjust the solids content to 30% solids.

The theoretical parameters of the product are as follows:

Solid (g) 84.29

PDMS (% solids) 16.09

NCO (unreacted) 0.0030

NMP (% product) 3

Amine (% product) 0.79

Acid (% solids) 3.97

HMDI (% solids) 24.37

Esters (% solids) 26.10

Ether (% solids) 32.17

Example 3

A jacketed reactor equipped with a pitched blade stir bar was maintained at 80°C and the following ingredients were added: 46.25 g (0.025 mole) Q2-5187, 5.00 g (0.05 mole) succinic anhydride, and 10.60 g N-methylpyrrolidone . After a reaction time of 2 hours, 10.76 g of N-methylpyrrolidone, 8.04 g (0.06 mol) of bis(hydroxymethyl)propionic acid and 33.02 g (0.127 mol) of ^DESMODUR® W were added. After 1 hour, 13.00 g (0.013 moles) of ^CARBOWAX® polyethylene glycol 1000 was added, followed by reaction for 3 hours. The system was cooled to 35°C and ionized by adding a mixture of 3.56 g (0.04 mole) dimethylethanolamine and 80.00 g deionized water. After an additional 5 minutes of mixing, the chain extender solution, 4.50 g of 33% ethylenediamine and 60 g of water, was added. After mixing for another 20 minutes, 63 g of water were added. After mixing for an additional hour, 100 g of water was added to adjust the solids content to 25% solids.

The theoretical parameters of the product are as follows:

Solid (g) 106.81

PDMS (% solids) 25.98

NCO (unreacted) 0.004

NMP (% product) 5

Amine (% product) 0.83

Acid (% solids) 2.53

HMDI (% solids) 30.91

Ether (% solids) 29.49

Example 4

A jacketed reactor equipped with a pitched blade stir bar was maintained at 80°C and the following ingredients were added: 56.50 g (0.025 mole) Q4-3667, 5.00 g (0.05 mole) succinic anhydride, and 10.00 g N-methylpyrrolidone . After a reaction time of 2 hours, 32.89 g (0.1265 mol) of ^DESMODUR® W were added. After 1 hour, 5.36 g (0.04 mol) of bis(hydroxymethyl)propionic acid, 35.00 g of FOMREZ® ^11-56 and 6.46 g of N-methylpyrrolidone were added, followed by reaction for 3 hours. The system was cooled to 35°C by adding, 3.56 g (0.04 mole) dimethylethanolamine and 50.00 g deionized water. After an additional 10 minutes of mixing, 276 g of water were added, followed by the chain extender solution, 7.20 g of ethylenediamine and 60 g of water. The solids content is 30% solids.

The theoretical parameters of the product are as follows:

Solid (g) 137.15

PDMS (% solids) 16.48

NCO (unreacted) 0.004

NMP (% product) 3

Amine (% product) 0.65

Acid (% solids) 1.31

HMDI (% solids) 23.98

Esters (% solids) 25.52

Ether (% solids) 24.72

Example 5

A jacketed reactor equipped with a pitched blade stir bar was maintained at 80 °C and the following ingredients were added: 56.50 g (0.025 moles) of Q4-3667, 7.60 g (0.05 moles) of tetrahydrophthalic anhydride, 1.01 g ( 0.01 mol) triethylamine and 10.0 g N-methylpyrrolidone. After a reaction time of 3 hours, 5.36 g (0.04 mol) of bis(hydroxymethyl)propionic acid and 6.77 g of N-methylpyrrolidone were added. After 5 minutes, 32.89 g (0.127 mol) of ^DESMODUR® W were added. After a reaction time of 1 hour, 35.00 g (0.018 mol) ^of FOMREZ® 11-56 were added and reacted for 3 hours. The system was cooled to 35°C and ionized by gradually adding 4.04 g (0.04 mol) of triethylamine and 50 g of ice water over 5 minutes. After an additional 10 minutes of mixing, 195.0 g of water was added over 10 minutes, followed by the chain extender solution, 7.20 g of 33% aqueous ethylenediamine and 60 g of ice water, over 12 minutes and the mixture was further mixed for 3 hours at 25°C.

The theoretical parameters of the product are as follows:

Solid (g) 139.75

PDMS (% solids) 16.17

NCO (unreacted) 0.004

NMP (% product) 3

Amine (% product) 2.08

Acid (% solids) 1.29

HMDI (% solids) 23.53

Esters (% solids) 25.04

Ether (% solids) 24.26

The following examples illustrate the preparation of constructions according to the invention as well as the release characteristics and ink printability of the release coatings of the invention.

Example A

The emulsion of Example 1 was applied to a postage stamp paper using a No. 12 Meyer rod using a laboratory test coater. The coated stamp paper was then placed in an oven at about 155°C for 2 minutes to dry the emulsion. After cooling, three 1 inch wide strips of S-2176 hot melt pressure sensitive adhesive tape were placed on the coated surface with a rubber roller applying pressure at 20 psi. These press-up tapes were aged under Kiel aging test conditions: 70°C, 0.25 psig for 24 hours. The average release force at a speed of 300 inches/minute was 56 g/inch. The release coating has a drying time of less than 2 minutes for USPS inks (diol-based) and the inks are permanently capped. These data show that the release coating of Example 1 has very good ink printability and release efficiency.

Example B

The emulsion of Example 2 was applied to a postage stamp paper using a No. 12 Meyer rod using a laboratory test coater. The coated paper was then placed in an oven at 155°C for 2 minutes to dry the emulsion. After cooling, three 1 inch wide strips of P-5001 hot melt pressure sensitive adhesive tape were placed on the coated surface with a rubber roller applying pressure at 20 psig. These press-up tapes were aged under Kiel aging test conditions: 70°C, 0.25 psig for 24 hours. The average release force at a speed of 300 inches/minute was 37 g/inch. The release coating has a drying time of less than 2 minutes for USPS inks (diol-based) and the inks are permanently capped. These data also show that the release coating of Example 2 has very good ink printability and release efficiency.

While the invention has been described in relation to its preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art from the reading of the specification. It is therefore to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims.

Claims (24)

1. An unlined, release coating for substrates with pressure sensitive adhesives, said release coating being adapted for printing ink receptivity, said release coating comprising a composition comprising: A reaction product of a mixed emulsion of: (A) at least one of polydimethylsiloxane with carboxylic acid end, polydimethylsiloxane with isocyanate end, or a mixture thereof (B) a hydrophilic isocyanate-reactive reagent; (C) a polyisocyanate; and (D) At least one of a dihydroxy-terminated oligomer, a diamino-terminated oligomer, or a mixture thereof. 2. The release coating of claim 1, wherein the reaction product further comprises (i) the residue of an ionized tertiary amine; and (ii) the residue of a chain-extending diamine. 3. The release coating of claim 2, wherein the tertiary amine is at least one of trialkylamine, pyridine, and N,N-dimethylethanolamine; and wherein the diamine is derived from isophorone di Amine, di-omega-amino polyether, piperazine, hydrazine, aminoethylpiperazine, (polymethylene)diamine, and xylylenediamine. 4. The release coating of claim 1, wherein the carboxylic acid-terminated polydimethylsiloxane (A) is a combination of a dihydroxy-terminated polydimethylsiloxane and a cyclic anhydride. A reaction product, and polydimethylsiloxane (A) with isocyanate terminal is a polyisocyanate and a polyisocyanate with at least one of -CO ₂ H, -OH, -NHR, -NH ₂ and thiol functional groups A reaction product of polydimethylsiloxane. 5. The release coating of claim 1, wherein the hydrophilic isocyanate-reactive agent (B) is a linear or branched aliphatic monomer characterized by at least one of the following two: (i) Contains two primary hydroxyl groups and one tertiary carboxylic acid group, or (ii) contains two primary hydroxyl groups and one tertiary sulfonic acid group. 6. The release coating of claim 5, wherein the monomer contains 4 to 20 carbon atoms. 7. The release coating of claim 1, wherein the polyisocyanate (C) is at least one of: (i) an organic diisocyanate; (ii) a heating reaction product of a phenol ketone oxime; or (iii) a A blocked polyisocyanate, optionally wherein the blocked polyisocyanate is a reaction product of phenol ketoxime, polyisocyanate, and caprolactam. 8. The release coating according to claim 1, wherein the dihydroxy-terminated oligomer (D) is at least one of a dihydroxy-terminated polyether oligomer and a dihydroxy-terminated polyester oligomer . 9. The release coating according to claim 8, wherein the dihydroxy-terminated oligomer (D) contains at least one functional group selected from the group consisting of ethers, esters, alkylenes, and olefins ; and optionally wherein the dihydroxy-terminated oligomer (D) contains alcohols, amines, carboxylic acids, carboxylates, amides, anhydrides, imides, thiols, phosphoric acid , phosphates, sulfonic acids, sulfonates and sulfates at least one additional functional group selected from the group consisting of. 10. The release coating of claim 9, wherein oligomer (D) is further characterized as having a number average molecular weight greater than 100. 11. The release coating of claim 1, wherein the diamino-terminated oligomer (D) is at least one of a diamino-terminated polyether oligomer and a diamino-terminated polyester oligomer . 12. The release coating according to claim 11, wherein the diamino-terminated oligomer (D) contains a compound selected from ethers, esters, alkylenes, olefins, alcohols, amines, carboxylic acids, carboxyl At least one functional group selected from the group consisting of salts, amides, acid anhydrides, imides, thiols, phosphoric acid, phosphates, sulfonic acids, sulfonates and sulfates. 13. An ink-imprintable stamp or label construction comprising a plurality of consecutive stamps or labels in a roll or stacked sheet configuration without a separate release liner, wherein the stamps or labels are on the reverse side of the stamps or labels Having a pressure sensitive adhesive and having a release coating on the front of the stamp or label, said release coating comprising a release coating according to any one of claims 1-7. 14. The ink-imprintable stamp or label construction of claim 13, wherein the pressure sensitive adhesive is one of a hot melt adhesive, a water soluble or water dispersible adhesive, and an organic soluble adhesive. 15. The ink-imprintable stamp or label construction of claim 14, wherein the pressure sensitive adhesive comprises an acrylic emulsion adhesive. 16. An ink-imprintable stamp or label construction comprising a plurality of consecutive stamps or labels in a web configuration without a separate release liner, wherein the stamps or labels each comprise (A) a layer of ink-imprintable material having a front side and a back side; (B) an ink embossable release coating bonded to the front side of the material; said release coating comprising the release coating of any one of claims 1-7; and (C) a layer of pressure-sensitive adhesive in contact with and bonded to the other side of the material, whereby the stamp or label construction maintains the crimped configuration by the cooperative action of the pressure-sensitive adhesive layer and the release coating type, and the adhesion between the release coating and the face of the layer of ink-imprintable material is greater than the force required to separate the release coating from the pressure-sensitive adhesive when the stamp or label construction is unrolled , optionally wherein the pressure sensitive adhesive is one of a hot melt adhesive, a water soluble or water dispersible adhesive and an organic soluble adhesive. 17. The ink-imprintable stamp or label construction of claim 16, wherein the layer of ink-imprintable material (A) is paper. 18. The ink-imprintable stamp or label construction of claim 16, wherein the pressure sensitive adhesive comprises an acrylic emulsion adhesive. 19. An ink embossable tape construction wherein the tape has a pressure sensitive adhesive on the back of the tape and a release coating on the front of the tape, said release coating comprising the The release coating of any of , optionally wherein the pressure sensitive adhesive is one of a hot melt adhesive, a water soluble or water dispersible adhesive and an organic soluble adhesive. 20. The ink-imprintable tape construction of claim 19, wherein the pressure sensitive adhesive comprises an acrylic emulsion adhesive. 21. An ink imprintable construction comprising a substrate in roll or stacked sheet configuration without a separate release liner, wherein the substrate has a pressure sensitive adhesive on the back of the substrate and The front side of the substrate has a release coating comprising the release coating according to any one of claims 1-7. 22. The ink-imprintable construction of claim 21, wherein the pressure sensitive adhesive is one of a hot melt adhesive, a water soluble or water dispersible adhesive, and an organic soluble adhesive. 23. The ink-imprintable construction of claim 22, wherein the pressure sensitive adhesive comprises an acrylic emulsion adhesive. 24. The ink-imprintable construction of claim 21, wherein the construction is at least one of a postage stamp, a label, gift wrap tape, a direct thermal construction, or a heat transfer construction.