WO2012134695A1 - Film coatings based on polyalkylimine condensation polymers - Google Patents

Abstract

Provided is a composition, preferably VOC-free, comprising the condensation product of a polyalkylimine and one or more amine-reactive molecules, and films coated with the condensation product. The coatings are applied to the films to provide a dried coating weight of less than 0.30 g/m2. Preferred amine-reactive molecules include acetylacetonate, methyl acetonate, ethyl acetoacetonate, glycidyl methacrylate, methyl methacrylate, and mixtures thereof.

Description

FILM COATINGS BASED ON POLYALKYLIMINE

CONDENSATION POLYMERS

CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to PCT/US201 1/030345 filed March 29, 201 1, and to U.S. Provisional Patent Application 61/540,802 filed on September 29, 2011. FIELD OF THE INVENTION

[0002] The present invention relates to film coatings to promote printing ink adhesion, and more particularly to film coatings based on condensation polymers of polyalkylimines. BACKGROUND

[0003] Current clear pressure sensitive film labels work very well, but often contain volatile organic compounds ("VOCs") that constrain the allowed coating weights. Moreover, a key raw material in prior art coatings, such as disclosed in US 6,893,722, is often limited in the number of suppliers in the market. Therefore, there is a need for newer film coatings that reduce the VOCs and for which the raw materials are less specialized.

[0004] The inventor has found a way to retain some essential advantages of coatings, as in US 6,893,722, that yield excellent UV printability and print durability (IPA resistance, pasteurization resistance, etc.) but without VOCs and without the need of a complex condensation/grafting process (and the associated equipment constraints). Moreover, the new technology described herein appears to offer utility beyond just pressure sensitive labels. Due to their chemical composition and efficacy at extremely low coating weights, the coatings described herein offer a broad range of film applications.

[0005] Related prior publications include US 6,297,328; US 5,296,530; US 5,525,662; US 5,498,659; US 5,81 1, 121; US 5,380,587; US 5,382,473; US 5,419,960; US 5,789,123; US 5,827,627; and US 201 1/0254909 and US 2007/024881 OA 1.

SUMMARY

[0006] Provided is a composition comprising the condensation product of a polyalkylimine and one or more amine-reactive molecules comprising (or selected from the group consisting of in another embodiment) at least one of:

Rc=c(_Ra)_(cx₂)_j-C(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX_{2 (1 )} or (and)

Y-(CX₂)m-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX_{2 (2)} where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and selected from the group consisting of H and C^ to C^ alkyl; R^c is selected from the group consisting of O and CX2; each X can be the same or different and is selected from the group consisting of H, hydroxyl, halogen, and any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is selected from the group consisting of O and NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

[0007] Alternatively, the moieties above for formulas (1) and (2) can be defined where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and are H or a Ci to alkyl; R^c is O or CX2; each X can be the same or different and is H, hydroxyl, halogen, or any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is O or NR^d; CR^d and CR¾ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

[0008] Also provided is a film comprising at least one polymer layer having a first and second side, further comprising a coating on at least the first side, wherein the coating is the condensation product of a polyalkylimine and one or more amine-reactive molecules comprising (or selected from the group consisting of) at least one of:

_Rc₌c(_Ra)_(cx₂)_rC(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂ or (and)

Y_(cx₂)_m-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂

where each group has the same meaning as above.

[0009] The various descriptive elements and numerical ranges disclosed herein can be combined with other descriptive elements and numerical ranges to describe the invention(s); further, any upper numerical limit of an element can be combined with any lower numerical limit of the same element to describe the invention(s).

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a graphical representation of tests showing the relationship between the coating weight (on a test film) of an inventive condensation polymer versus its adhesion (O-Ink-2 method).

[0011] Figure 2 is a graphical representation of tests showing the relationship between the coating weight of an inventive condensation polymer versus its adhesion having had prior UV exposure (5-Ink-2 method). [0012] Figure 3 is a graphical representation of tests showing the relationship between the coating weight of an inventive condensation polymer versus its adhesion in water (0-Ink- 2)·

[0013] Figure 4 is a graphical representation of tests showing the relationship between the coating weight of an inventive condensation polymer versus its adhesion in water having had prior UV exposure (5-Ink-2).

[0014] Figure 5 is a graphical representation of tests showing the relationship between the coating weight of an inventive condensation polymer and the blocking force of the film having the coating thereon.

DETAILED DESCRIPTION

[0015] Disclosed herein are compositions comprising the condensation product of polyalkylimines with certain amine-reactive molecules, thus forming condensation polymers. The compositions tend to form soluble or substantially soluble compositions in aqueous media at and above pH 8. By "aqueous", what is meant is a diluent comprising at least 50 wt% or 60 wt% or 70 wt% or 80 wt% water, and preferably comprising at least 95 wt% or 100 wt% water. The compositions are particularly useful as coatings on films. Such coatings are present in a sufficient amount to enhance the printability of ink on the film surface, and preferably, to maintain the ink on the surface for extended periods with typical wear and moisture conditions. The coatings can be a primer, which is a coating layer that is in between the primary printable coating and the film to enhance the adhesion of the printable coating to the film structure. The coatings may also serve as the primary printable coating itself. In either case, one advantage of the condensation polymers is that they require very low loadings compared to current coatings. In certain embodiments, the coating weight on the film surface (either as a primer or as the primary printable coat) is less than 0.30 or 0.20 or 0.15 or 0.10 g/m²; or within the range from 0.001 or 0.01 to 0.10 or 0.15 or 0.20 or 0.30 g/m².

[0016] Another advantage to the coating compositions described herein is that they are free of volatile organic compounds ("VOC"). Thus, in certain embodiments are described compositions and coatings that are free of VOCs. VOC's are organic chemicals that have a high vapor pressure at ordinary, room-temperature conditions, non-limiting examples of which include formaldehyde, ethyl alcohol, hexane, terpenes, toluene, and acetone. [0017] In one aspect is a composition comprising the condensation product of a polyalkylimine and one or more amine-reactive molecules comprising (or selected from the group consisting of in another embodiment) at least those in formulas (1) and (2):

Rc=c(Ra)_(CX₂)_j-C(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂ (1) and

Y-(CX₂)_m-(0-[CR¾]_q)_p-A-C(0)-C(Rb)=CX₂ (2) where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and selected from the group consisting of H and to C alkyl; R^c is selected from the group consisting of O and CX₂; each X can be the same or different and is selected from the group consisting of H, hydroxyl, halogen, and any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is selected from the group consisting of O and NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

[0018] In one embodiment, R^c is oxygen (O); R^a and R^b is methyl or H; X and R^d is hydrogen (H); j is 1 ; k is 0; q is 2; p is 1 ; and A is oxygen (O). In another embodiment, Y is a three-membered oxirane ring (CH₂(0)CH₂); m is 1; p is 0; A is oxygen (O); R^b is methyl (— CH3); and X is hydrogen (H). In desirable embodiments, the amine-reactive molecule is selected from the group consisting of acetylacetonate, methyl acetonate, ethyl acetoacetonate, glycidyl methacrylate, methyl methacrylate, and mixtures thereof.

[0019] The polyalkylimine ("PAI") can be any oligomer or polymer, or mixture thereof, having at least one "imine" group (— N(H)~ ) incorporated therein. Desirably, the imine group(s) is part of the polymer backbone. In one embodiment, the polyalkylimine is an imine containing polymer comprising C₂ to C Q alkyl or alkenyl-derived units in the backbone. Preferably, the PAI comprises imine-derived units and alkyl-derived units, and most preferably, the PAI consists of imine groups and alkyl-derived units. Preferably, the PAI is selected from the group consisting of polyethyleneimine, polypropyleneimine, polypropyl-co- ethyleneimine, and mixtures thereof. In particular embodiments, styrenic-derived units, such as present in styrenated acrylic resin, are absent from the polyalkylimine. In any case, the PAI preferably has a weight average molecular weight (M_w) of from 3,000 or 5,000 or 10,000 or 20,000 or 40,000 to 80,000 or 100,000 or 150,000 or 200,000 or 300,000 or 500,000 or 1,000,000 or 2,000,000 amu. [0020] The condensation polymers described herein are typically produced in an aqueous solution by combining the amine-reactive molecules with a PAL Amine-reactive molecules are molecules that include at least one moiety that will react with an amine/imine to form a covalent or ionic chemical bond, preferably covalent. Desirably, there are from 0.1 or 0.2 to 0.6 or 0.8 or 1.0 or 1.1 or 1.2 or 2.0 or 2.5 or 3.0 amine-reactive equivalents ("ARE") of the amine-reactive molecules that are combined with the PAL Desirably, the product can be isolated from an aqueous diluent in solution or substantially in solution at a pH of at least 8. The product of the condensation reaction between the PAI and amine-reactive molecule is the condensation polymer as described herein, but in certain embodiments it is not necessary to specifically isolate the condensation polymer from the reaction medium, hence, in certain embodiments, the usefulness of the condensation polymer is as the entire mixture or condensation product. The condensation polymer can be used for coating in solutions or suspensions at most any pH, and in certain embodiments, the composition, when used as a coating, is a suspension having a solids content within the range of from 0.1% or 0.5% or 1% to 3% or 4% or 5% or 8% or 10% or 30% or 50% or 60%, by weight of the coating.

[0021] The PAI coatings of the invention may also be further modified or cross-linked by either chemical means or radiative means. Secondary alkylamines are known to undergo Michael-type additions reactions at room temperature with ethenically unsaturated compounds like methyl acrylate, acrylonitrile, and many other materials with similar functionality (Mather et al., 31 Progress in Polymer Science, 487-531 (2006)). Typical Michael-acceptors that are a, β-unsaturated carbonyl compounds are thus preferred in cross- linked PAIs to further modify or cross-link PAIs. Examples of non-cross-linking Michael- type PAI modifiers include acrylates (for example, methyl acrylate, 2-hydroxyethyl acrylate, acrylamide) or acrylonitrile. To significantly increase the molecular weight of the PAI, the polymer can be cross-linked with poly-functional acrylates such as 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate (PETA), or other readily available materials, some of which contain varying degrees of ethoxylation or propoxylation.

[0022] A desirable use of the condensation product is in coatings for films. Thus, in one aspect of the invention, described herein is a film comprising at least one polymer layer having a first and second side, further comprising a coating on at least the first side, wherein the coating is the condensation product of a polyalkylimine and one or more amine-reactive molecules selected from molecules of formulas (1) and (2) as described above. The "film" can be made of most any material and can be multiple layers of materials as is known in the art. Desirably, the condensation product is adhered to at least one external surface of the film, understanding that any film in two-dimensions (ignoring its thickness) will have two external (first and second) surfaces. Thus, in one embodiment, the first and second sides of the film are coated with the polyalkylimine condensation product.

[0023] More specifically, in one embodiment, the film is a multi-layered film having outside surfaces on both sides of the film, wherein both of the outside surfaces are coated with the polyalkylimine condensation product. In certain embodiments, as mentioned above, the coating weight of the condensation product once dried on the film surface (first or second) is less than 0.30 or 0.20 or 0.15 or 0.10 g/m²; or within the range from 0.001 or 0.01 to 0.10 or 0.15 or 0.20 or 0.30 g/m².

[0024] In any case, in certain embodiments, the polymer used to make the film is selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acrylate, nylon, polyester, and mixtures (and/or layers) thereof. In a particular embodiment the polymer is polypropylene, which can be any polymer having at least 50 wt%, by weight of the polymer, of propylene-derived units. In a particular embodiment, the polymer is polypropylene. The "polypropylene" is a polymer comprising from 98 wt% to 100 wt% propylene-derived units and can be made by any desirable process using any desirable catalyst as is known in the art, such as a Ziegler-Natta catalyst, a metallocene catalyst, or other single-site catalyst, using solution, slurry, high pressure, or gas phase processes. The polypropylenes have a melting point determined by ASTM D3418 of at least 130°C or 140°C, or within a range from 130°C to 180°C. A "highly crystalline" polypropylene is a preferred polypropylene useful in certain embodiments, and is typically isotactic and comprises 100 wt% propylene-derived units (propylene homopolymer) and has a relatively high melting point of from greater than (greater than or equal to) 140°C or 145°C or 150°C or 155°C or 160°C or 165°C as measured by ASTM D3418.

[0025] The term "crystalline," as used herein, characterizes those polymers which possess high degrees of inter- and intra-molecular order. In certain embodiments, the polypropylene has a heat of fusion (H_f) greater than 60 J/g or 70 J/g or 80 J/g, as determined by DSC analysis. The heat of fusion is dependent on the composition of the polypropylene; the thermal energy for the highest order of polypropylene is estimated at 189 J/g that is, 100% crystallinity is equal to a heat of fusion of 189 J/g. A polypropylene homopolymer will have a higher heat of fusion than a copolymer or blend of homopolymer and copolymer.

[0026] In any case, in certain embodiments, the polypropylene has a melt flow rate ("MFR", 230°C, 2.16 kg, ASTM D1238) within the range of from 0.1 or 0.5 or 1 to 4 or 6 or 8 or 10 or 12 or 16 or 20 g/10 min. Also, in any case, the polypropylene may have a molecular weight distribution (determined by GPC) of from 1.5 or 2.0 or 2.5 to 3.0 or 3.5 or 4.0 or 5.0 or 6.0 or 8.0. Suitable grades of polypropylene, and in particular, highly crystalline polypropylenes that are useful in oriented films include those made by ExxonMobil, LyondellBasell, Total, Borealis, Japan Polypropylene, Mitsui, and other sources.

[0027] In a particular embodiment, the film having the coating comprises at least three layers, wherein a core layer comprises polypropylene, and at least one skin layer is adhered to the first and second sides of the core layer. Even more particularly, there may be tie-layers between one or both skin-core interface. Thus, the final structure may be one of A/B/C/B/A, wherein "A" is a skin layer, where each layer may be made of the same or different materials, "B" is a tie-layer (each the same or different), and "C" is a core layer. Desirably, the polyalkylimine condensation product is coated on at least one skin layer. In certain embodiments, the first side of the film has ink printed thereon, and the second side has adhesive adhered thereto.

[0028] The film can be coated by any suitable means. Preferably, the coating is applied to a film using a gravure coater, the coating composition having a solids level within the range of from 0.5 or 1.0 wt% to 4 wt% or 5 wt% or 6 wt%. When a primer is present, the primer may be similarly applied.

[0029] Any one or all of the layers may have certain additives included with the primary polymer materials used to make the layers. The condensation product coating may also comprise similar additives. In a particular embodiment, however, anti-blocking agents are substantially absent from the coating. Anti-block agents can be an actual film layer such as polyethylene, but can also be an additive to a film layer such as silica or other additive as is known in the art. In any case, when present, the condensation product coating comprises from 1 wt% or 5 wt% or 10 wt% to 20 wt% or 30 wt% or 40 wt% or 50 wt% anti-block agent. With or without the oxidation treatment or anti-blocking agents, in certain embodiments the coefficient of friction of the coated film is less than 1 or 0.8 or 0.5 or 0.4.

[0030] In any case, other "additives" include compositions such as cavitating agents (e.g., CaC03), opacifying agents, pigments, colorants, slip agents, antioxidants, anti-fog agents, anti-static agents, fillers, moisture barrier additives, gas barrier additives, and combinations thereof, as discussed in further detail below. Preferably, the total amount of additives, including cavitating agents, in the first skin layer ranges from about 0.2 wt% or 0.5 wt% to 2 wt% or 4 wt% or 8 wt% or 10 wt% or 20 wt% or 40 wt%. In certain embodiments, the anti- block is not an additive but is an oxidation treatment of the skin surface such as a plasma, corona or flame treatment as is known in the art.

[0031] Preferably, primers are present in the coated films. Most preferably, the primary component of the primer is the same or similar to the coating polymer, but with other additives. Most preferably, PAIs are used as primers. In certain embodiments, the primer consists essentially of a PAI as described herein.

[0032] Throughout the specification, when stating "consisting essentially of what is meant is that the any other components and/or additives, if present, are present to no more than 1 wt% or 2 wt% or 3 wt% or 5 wt% of the claimed composition.

[0033] The coated films described herein have many uses, but are particularly desirable in labels, such as adhesive labels, especially labels for printing and attaching to articles of manufacture, and most preferably pressure sensitive labels where printing is required. Most preferably, the inventive films are coated on the side of the film to be printed upon, or "print side" of the film. The usefulness of this is demonstrated in the following non-limiting examples.

EXAMPLES

Example 1. Condensation Polymer Stability at Elevated pH

[0034] This example merely distinguishes the physical characteristics of the inventive condensation polymers from polymers described in US 6,893,722. That patent disclosed that the polymer therein exists as a stable emulsion or solution in water only when the pH is < 8. Polymer Example A (from the '722 patent, col. 29) was diluted to 10% solids. An attempt was made to increase the pH of this emulsion by adding ammonia to about 100 mL of the emulsion that was being stirred in a beaker with a Teflon-coated stirring bar. Addition of ammonia to the emulsion caused localized coagulation. Before the pH exceeded 7.0, the entire beaker of coating had solidified. This result is consistent with a similar condensation reaction described in the '722 patent with a different polymer backbone.

[0035] In a separate beaker, a blend containing 100 parts (on a dry basis) Mica™ H760A (from Mica Corporation, M_w greater than about 500,000) and 175 parts acetoacetoxyethyl methacrylate (AAEM) diluted to 10% theoretical solids with water was also stirred. The condensation reaction was allowed to go to completion. The initial pH of this blend was about 6.9. Ammonia was added to the reaction product and the pH increased to 9.5 without any sign of kick out or coagulation. This demonstrates that the polymers from this invention are stable at pH values greater than 8 and, therefore, distinct from the polymers in the 722 patent having the styrenic-containing backbone.

[0036] In general, condensation polymers described herein are believed to be much easier to formulate than polymers from the 722 patent, because the pH can be increased with bases like ammonia or lowered with acids like acetic acid. In contrast, it has been shown to be difficult to increase the pH of polymers from the 722 patent, because of coagulation issues.

[0037] Several blends in Example 2 also have pH values above 8 at the end of reaction without any subsequent pH adjustment. While polymer emulsions from this invention are stable at pH values greater than 8, it is still within the scope of this invention to use coating formulations containing condensation polymers that are at pH values below 8.

Example 2. Synthesis of Condensation Polymers

[0038] Several condensation polymers were made using polyalkylimines (PAIs) like Mica™ H760A or Epomin™ PI 050 (PEI, polyethylene imine from Nippon Shokubai, M_w about 70,000) and a material containing acetoacetate functionality (ethyl acetoacetate [EtOAcAc] or acetoacetoxy ethyl methacrylate [AAEM] or oxirane functionality (glycidyl methacrylate [GMA]). The blends were prepared by mixing the amino-functional polymer with water. Once dispersed, the modifier [acetoacetonate ("AcAc")-functional material or oxirane- functional material] was added. At > 10% solids, the modifiers were added while the poly-amine was stirring to minimize precipitation. The following Table 1 summarizes the blends that were prepared:

Table 1

Mica Turbid, bright yellow;

8 100 AAEM 175 0.817 1.5 7.07

H760A 3.2 cP

Mica Turbid, bright yellow;

9 100 AAEM 200 0.934 1.5 7.00

H760A 3.0 cP

Mica

10 100 EtOAcAc 25 0.192 1.5 8.63 Clear, amber

H760A

Mica

11 100 EtOAcAc 75 0.576 1.5 8.14 Clear, bright yellow H760A

Mica

12 100 EtOAcAc 125 0.961 1.5 7.69 SI. turbid, yellow

H760A

Mica

13 100 EtOAcAc 175 1.34 1.5 7.57 SI. turbid, yellow

H760A

Mica Turbid, bright yellow;

14 100 AAEM 200 0.934 3 7.64

H760A 3.0 cP

Mica Turbid, bright yellow;

15 100 AAEM 200 0.934 4 7.62

H760A 3.0 cP

Mica Turbid, bright orange; 3.4

16 100 AAEM 100 0.467 3 8.23

H760A cP

Mica Turbid, bright orange; 3.6

17 100 AAEM 100 0.467 4 8.22

H760A cP

Mica Turbid, bright orange; 11

18 100 AAEM 100 0.467 10 8.25

H760A cP

Mica Turbid; bright yellow; si.

19 100 AAEM 200 0.934 10 7.59

H760A grit; 3.6 cP

Mica Bright yellow; gritty; 3.8

20 100 AAEM 200 0.934 15 7.63

H760A cP

Mica

21 100 AAEM 200 0.934 20 — Gelled in <15 minutes.

H760A

22 P1050 100 AAEM 500 2.34 6 7.73 SI. turbid; v. little color

SI. turbid; v. little color;

23 P1050 100 AAEM 500 2.34 10 7.49

4.5 cP

Clear; v. little color; 5.9

24 P1050 100 EtOAcAc 300 2.30 10 8.73

cP

Mica Bright yellow; grit-free;

25 100 AAEM 175 1.34 10 7.63

H760A 3.6 cP

Mica

26 100 GMA 133 0.936 10 7.37 Clear, amber; 6.3 cP H760A

[0039] For purposes of calculating the blending ratios, it was assumed that Mica H760A was 12% solids; Epomin™ P 1050 was 50% solids, and the AcAc and glycidyl additives were treated as 100% active. The pH values were measured between one and four days after the initial blends were made. For a few selected samples the pH changes versus time were monitored. Generally speaking, the pH stabilized within 24 hours of mixing the components indicating that the condensation reactions were substantially complete within one day. [0040] To simplify comparisons among modifiers having different equivalent weights, the above table normalizes the parts of modifier per hundred parts of the PAI (phr) into the number of amine-reactive equivalents ("ARE") per hundred parts of PAI. Therefore, for example, when Mica™ H760A is the PAI, 200-phr AAEM will functionalize, on a molar basis, about the same number of amine groups as 133-phr GMA. If polyethylene imine were strictly a linear polymer, then the repeat unit would be about 45 g/equivalent. Therefore, it would theoretically take 2.22 ARE to fully functionalize lOOg (100 parts) of a linear PEI molecule. Chain branching or other chemical modification of the polyalkylimine would affect the amount of amine groups that would be available for reaction with modifiers described in this invention. While not wanting to be bound by theory, one could anticipate that < 2.5 AREs would be sufficient to fully functionalize PAIs based on polyethylene imine (allowing for a slight molar excess of the modifier to help increase reaction rates and/or to increase the equilibrium concentration of the condensation polymer). Since the exact chemical compositions of commercially available PAIs are not generally known to those outside the supplying company, suitable blend ratios must be determined empirically for each PAI type.

[0041] Blends 19, 20, and 21 were the only ones that showed any evidence of grit formation from the chemical reaction. Other than Blend 21, all samples were low viscosity at the end and/or in-process. AAEM blends had very little odor after the reaction was complete. Blends with EtOAcAc or GMA had more noticeable odors.

[0042] Blends 23 and 24 from Example 2 were applied to the print surface of Label- Lyte™196 LL B2 from ExxonMobil using a lab-scale coater, which applied coating directly to the substrate a 200-Quad gravure cylinder at about 40 feet/min. The coating was dried at 99°C in an oven that was about 4 feet long. Formulations in Table 2 are based on 100 parts condensation polymer. Before applying the twelve topcoats below, the same line conditions were used to prime the film with a solution containing 0.1% Mica H760A that was adjusted to pH 10 with ammonia. The estimated coating weight of the primer is about 0.003 g/m². Inline corona treatment was used to improve the wet out of the primer, but no corona treatment was used when coatings were applied to primed film. Some topcoat formulations contained colloidal silica (Ludox™ CLP from Grace Davison), which reduces the tendency of the printable surface to stick to the adhesive-receiving surface on the other side of the film. All the coating formulations also contained 0.5% Hexyl Cellosolve™ (Union Carbide) to improve the uniformity of the coating lay down over the primer. [0043] Printability Tests: A 355.34.PW screen (supplied by Nor-Cote International, Inc., Crawfordsville, Ind.) and a squeegee were used to hand apply the black screen ink (UV -50 Mixing Black screen ink from Sun Chemical) to a 3-inch by 3-inch patch on the coated surface of a film sample. After applying the ink, it was cured by passing the printed sample twice under the UV curing lamp in an apparatus built by Fusion Systems® at 100 feet per minute. The cured ink was about 7 microns thick.

[0044] To simulate print performance in the first station of a multi-station printing press, samples were printed with ink on test surfaces that had no prior exposure to UV light followed by two passes under the UV lamp to cure the ink. This is the "O-Ink-2" curing protocol. Each pass under the UV lamp typically exposed the sample to an energy equivalent that was between 0.09 and 0.12 Joules/cm².

[0045] To simulate print performance in one of the latter stations of a multi-station printing press, test surfaces were passed five times under the UV lamp at 100 feet per minute prior to the application of ink (followed by an additional two passes to cure the ink). This is the "5-Ink-2" curing protocol.

[0046] After samples were printed, initial ink adhesion was tested using three strips of 1- inch wide Scotch™ 600 tape laid across the entire 3 x 3-inch patch of cured black screen ink and air bubbles were pressed out by hand. After leaving the tape on the surface for 1 to 2 minutes, each strip of tape is rapidly peeled off. Samples were rated on the percentage of ink left on the entire 3 x 3 block after all three pieces of tape have been removed. The amount of ink remaining was recorded as the %INK.

[0047] Retained ink adhesion after immersion was tested in a similar fashion, but two different tapes were used and the dwell times were a little shorter. Printed samples were prepared using both curing protocols as described previously. After waiting four to seven days, samples were immersed for 24 ± 4 hours in deionized water. After patting the sample dry with a paper towel, three strips of 1-inch wide Scotch 610 were quickly applied to cover the entire 3 x 3 printed surface. After a dwell time of between 10 and 30 seconds, the tape was quickly removed, and then three 1-inch strips of Scotch 600 tape were immediately applied to the same printed area on the sample. After a dwell time of between 10 and 30 seconds, the Scotch 600 tape was quickly peeled off. The amount of ink left after being tested with both tapes was recorded as %TNK-W.

[0048] After coating, the samples were tested for %TNK and %TNK-W, as described in Example 3. The results are shown in Table 2. Table 2

[0049] While AAEM and EtOAcAc both form enamines with the polyalkylimine, results in Table 2 show that it is preferable for the condensation polymer to contain ethenic unsaturation (from AAEM in this example) when radiation-curable printing inks are used. The results also show that retained ink adhesion after immersion in water (%INK-W) was better when the condensation polymer of this invention was applied at a lower coating weight. Example 3 more completely describes the response of printability to changes in coating weight.

Example 3. Inventive and Comparative Example

[0050] This example will demonstrate that the embodiments of the polyalkylimine condensation product provides better print performance at coating weights that are much lower than taught in US 6,893,722.

[0051] In the '722 patent, coating formulations were applied at 5% solids using a 130- Quad gravure cylinder to the print surface of Label-Lyte 196 LL B2 from ExxonMobil Chemical Films Business, which would yield a coating weight of about 0.19 g/m² after drying at 250°F. These coated films were subsequently printed with a black UV-screen ink and evaluated for initial ink adhesion and adhesion after immersion in water.

[0052] Two preferred examples were selected from the '722 patent for the purposes of comparison with the current invention. From Example 7 (US '722), the coating composition described in Table 3 using Polymer A was recreated at 10% solids and applied using essentially the same coater and line conditions, except that a 200-Quad gravure cylinder was used. After coating a sample at 10% solids, serial dilutions with 0.5% hexyl-cellosolve in deionized water were used to create samples with coatings at 5%, 2%, 1%, and 0.67% solids so that ink adhesion as a function of coating weight could be evaluated. Similar sample sets were prepared using the coating composition described in Example 10 (Table 6, roll 8) of the 722 patent.

[0053] A condensation polymer consistent with the present invention (Blend 19 in Table 1) was prepared from a mixture of 5128 g Mica H760A (11.7% solids, 100 parts), 1200 g acetoacetoxy ethyl methacrylate (AAEM), and 1 1672 g deionized water (for 10% theoretical solids). After completion of the condensation reaction 0.5% Hexyl Cellosolve was added to ensure that the coating wet the substrate properly. A solution of 0.5% Hexyl Cellosolve was used for making the serial dilutions of this polymer.

[0054] Similarly, a condensation polymer consistent with the present invention (Blend 26 in Table 1) was prepared from a mixture of 73.4 g Mica H760A (1 1.7% solids, 100 parts), 11.4 g (glycidyl methacrylate inhibited with 50 ppm hydroquinone monomethyl ether from Sigma-Aldrich, 133 parts), and 1 15.2 g deionized water (for 10% theoretical solids). After completion of the condensation reaction, 0.5% Hexyl Cellosolve and 0.05% Tergitol™ 15S9 were added to ensure that the coating wet the substrate properly. For this condensation polymer, the addition of Hexyl Cellosolve alone was insufficient to yield robust wetting properties. A solution of 0.5% Hexyl Cellosolve and 0.05% Tergitol 15S9 was used for making the serial dilutions of this condensation polymer.

[0055] The compositions were coated on films. Coating weights were calculated based on the weight of wet coating used to cover about 10 m² of surface area (the web was 12.7 cm wide). The amount of dry coating was calculated from the percent coating solids times the amount of wet coating that was consumed. Sample length was determined by multiplying the line speed (determined with a tachometer from Extech Instruments) times the length of time that the coating station was engaged.

[0056] The black UV-screen ink used in the '722 patent was no longer available; therefore, we selected UVN-50 Mixing Black screen ink from Sun Chemical to evaluate ink adhesion using the following printability tests described above in Example 2. For %TNK, Figure 1 shows results for the O-Ink-2 curing protocol versus coating weight, and Figure 2 shows results for the 5-Ink-2 curing protocol. For %INK-W, Figure 3 shows results for the 0- Ink-2 curing protocol versus coating weight, and Figure 4 shows results for the 5-Ink-2 curing protocol.

[0057] With every curing protocol and test condition, the present coating composition yields good results with coating weights below 0.3 or 0.2 g/m², and most preferably below 0.1 g/m² and varying degrees of adhesion loss above 0.1 g/m². Just the opposite is true for examples from the 722 patent: Most results for coating weights below 0.1 g/m² were poor (less than 90%) and excellent above 0.1 g/m².

Example 3. Primers and Anti-block

[0058] High-performance label films in the industry usually have one side designated as the printable surface and the opposite side is designated as the adhesive-receiving surface (examples: from ExxonMobil: Label-Lyte 50LL539, Label-Lyte 50LL534 II; Rayoface™ CPA). Occasionally, roll stock laminators will apply the pressure-sensitive adhesive to the wrong side of the film due to improper labeling of the input film or improperly mounting the roll on the line. The result is wasted material that is unsuitable for printing.

[0059] It would be desirable to have a label facestock that is capable of receiving adhesive or ink (especially radiation-cured inks) to either side of the label stock. This is technically challenging, for each surface must be capable of adhering a broad range of adhesives and printing inks while maintaining a low affinity between the opposing sides of a two-side coated label facestock. This is very challenging even if different coatings are used on opposing sides. The examples will show that condensation polymer technology can create such structures with symmetrically coated films.

[0060] While it is possible to use primers well known in the art (for example, Epoxy per Steiner et al, US 4,214,039, Epomin™ P1050, Lupasol™ WF, Lupasol™ P, Mica™ H760A, Aquaforte™ 108W, etc.) examples will show that condensation polymers of this invention also make excellent primers for the formulated topcoat based on the condensation polymer. Moreover, while Mica H760A offers excellent properties when used as a primer, the structures tend to have a noticeable yellow color, which some end users might find undesirable. In contrast, similar structures prepared with a condensation polymer have very little color at all (See Example 4).

[0061] Example 3-1 (Print face as taught in US 6,893,722; adhesive-receiving according to US 2007/0248810A1). Using a custom-built pilot-scale coater having a station to apply and dry a primer via an offset roll and a topcoat station that applies coating via reverse direct gravure, a structure was prepared in which a block-resistant adhesive-receiving coating was applied at 0.30 g/m² to one side of primed Label-Lyte 196 LL B2 from ExxonMobil that comprised 100 parts MichemPrime™ 4983.15 (from Michelman, Inc.), 70 parts NeoCryl™ XK90 (from DSM NeoResins), Ludox™ AS40 (from Grace Davison), 15.6 parts AZCote™ 5800M (from Akzo Nobel), MichemLube™ 215 (from Michelman, Inc.), Multifex-MM™ (Specialty Minerals, Inc.), 0.3 parts Tergitol™ 15S9 (Union Carbide), and 5 ppm Foamaster™ 223 (Cognis). The topcoat was dried at 175°F.

[0062] The primer beneath the adhesive-receiving coating was Mica H760A applied at a thickness that yielded an optical density of between 0.060 and 0.065 when measured at 510 nm with a Radiachromic Reader (Far West Technology, Inc.) after a piece of Label-Lyte 196 LL B2 coated only with the primer was immersed for 30 seconds in a 0.83 g/L methanolic solution of the potassium salt of ethyl eosin (Sigma- Aldrich) that was rinsed with water and patted dry with a tissue. The primer was dried at 175°F. Line speed was set at 175 fpm and the film was treated with a bare-roll treater (from Pillar) with a power setting of 1.0 kW.

[0063] After preparing a one-side coated roll that was about 2000 feet long and 26 inches wide, the film was sent through the coater again with the same line conditions and primer so that the printable coating could be applied to the other side of the film.

[0064] The primer station contained a 200-Quad gravure cylinder that transferred the coating to an offset roll, which applied the coating to the film. The topcoat station was equipped with a 330-lpi ceramic gravure cylinder used as a kiss coater to apply the coating to the film while rotating at the same speed but in the direction opposite to that of the moving web.

[0065] The printable coating comprised 100 parts R11 17 XL (Owensboro Specialty Polymers, LLC), 30 parts Ludox CLP, 5 parts acetoacetoxy ethyl methacrylate (Sigma- Aldrich), 1 part MichemEmulsion™ 09730 (Michelman, Inc.), and 0.5 parts Tospearl™ 120 (Momentive Performance Materials Japan LLC). The coating weight for the printable surface was about 0.13 g/m² and was applied at 12% solids. The coating weights for this example were determined by weighing about 0.023 m² of coated film before and after the coatings were removed by hand extraction with methyl ethyl ketone.

[0066] Four days after the two-side coated structure was prepared, the 26-wide roll was slit into smaller rolls on a Dusenbery ribbon slitter. To look for blocking problems that might occur during shipment to tropical locations, a slit roll that was 4¾ inches wide and 1500 to 1700 feet long on a 3½-inch outside diameter ("OD") cardboard core was placed into a conditioning cabinet (Model 518 from Electro-tech System, Inc.) set at 50°C/50% RH for one week. After removing the roll from the conditioning cabinet, a small slab of film was taken from the outer portion of the roll for printing tests (see table), and the remainder of the roll was moved to ambient storage conditions. Six days later, an attempt was made to unwind the roll at about 600 feet/min on the Dusenbery ribbon slitter. [0067] After conditioning, this roll had very little color. When the roll was unwound, continuous hissing was heard, then near the core the web broke. It was observed that if the printable surface of this example were applied to both sides of the structure, it would not be possible to unwind the film at all after a week of conditioning in a tropical environment.

[0068] Example 3-2 (Example demonstrating the invention on a clear substrate) A two- sided coated roll was prepared, slit, and conditioned as described in Example 3-1 with the following differences. Mica H760A was applied in the pre-coat station such that the optical density at 510 nm after staining the dried primer (without a topcoat) with eosin dye was between 0.103 and 0.1 1 1.

[0069] Unlike Example 3-1, the same topcoat (applied over the top of the dried primer) was used on both sides of the film, which comprised 100 parts of the Mica/AAEM condensation polymer described in Table 1 (Blend 19) and 100 parts Ludox CLP. The calculated average coating weight (based on the total amount of topcoat used after coating both sides) was 0.0307 g/m² and was applied at 2% solids. The hand-extraction method used in Example 3-1 is not practical for such low coating weights.

[0070] After conditioning, this roll was noticeably more yellow than the roll in Example 3-1; however, the difference was not discernable to the eye when looking at only a few sheets. This roll unwound with less noise than Example 3-1. The web also broke very near the core, but closer examination revealed a coating defect caused by a wrinkle in the web that created a spot on the very edge of the slit roll in which the primer was not covered by the topcoat.

[0071] Example 3-3 (Example demonstrating the invention on a clear substrate) A two- sided coated roll was prepared as described in Example 3-2, except that the topcoat was applied at 3% solids to achieve a calculated coating weight of 0.0459 g/m².

[0072] This sample was slightly yellower than Example 3-2. Initially this sample showed no hissing when it was unwound after conditioning for a week at 50°C/50% RH. Toward the middle of the roll and down to the core, very light hissing was heard periodically (perhaps due to slight variations in the coating weight). This conditioned roll was unwound to the core without tearing.

[0073] Example 3-4 (Example showing the current invention on an opaque substrate) A two-side coated roll was prepared, slit, and conditioned as described in Example 3-2 with the following differences. Mica H760A was applied in the pre-coat station such that the optical density at 510 nm after staining the dried primer (without a topcoat) with eosin dye was between 0.146 and 0.158. The oven temperature for the primer was about 70°C.

[0074] After determining the coating weight for the primer on clear film, the adhesive- receiving surface was prepared by coating Label-Lyte™ 160 LL302, which is a cavitated white opaque substrate with the primer and a topcoat comprising 100-phr of a condensation polymer (Blend 19, Table 1), 100-phr Ludox CLP, and 15-phr barium sulfate (Blanc Fixe Micro Plus™ from Sachtleben, Duisburg, Germany) at a dry coating weight of about 0.03 s/m². The adhesive-receiving coating was dried at 88°C. Note the similarity between this adhesive-receiving coating and the printable coating in for Example 3-2. The barium sulfate enhances block resistance, but it would undesirably increase the haze of a clear film. Conceptually, this coating could have been applied to both sides of the cavitated substrate, and printability would have been acceptable on both sides.

[0075] The print-face coating was applied over the same primer on the opposite of the film in a second pass through the coater. The print-face coating was different than the coating used on the adhesive-receiving surface: 100-phr condensation polymer (Blend 19, Table 1), 30-phr Ludox CLP, 15-phr Blanc Fixe Micro Plus™ at a dry coating weight of approximately 0.023 g/m². The print-face coating was also dried at 88°C.

[0076] This sample had a very white appearance (not yellow). After conditioning a narrow slit roll for a week at 50°C/50% RH, it was possible to unwind this roll down to the core without tearing and only slight hissing near the core.

[0077] The following table shows ink adhesion (initially and after immersion in water) determined by the methods described in the comparative example.

[0078] This example shows that coatings of the present invention formulated for block resistance yield excellent printability, even after exposure to harsh conditions that might be experienced during shipping to a tropical climate. Moreover, results for the conditioned samples are superior to the disclosures in the 722 patent. Furthermore, excellent printability is available on both sides of the structure, and reduces the risk of a roll-stock laminator having to dispose of film in which the pressure-sensitive adhesive was applied to the wrong side of the film.

[0079] Ink applied to the adhesive-receiving side of Example 3-1 would yield essentially 0% adhesion for all the above tests and conditions. Moreover, attempts to enhance block resistance of Example 3-1 by increasing the amount of colloidal silica in the printable coating resulted in further degradation of the print performance, especially after immersion in water. Example 4. Primer Layer

[0080] This example shows that condensation polymers of the present invention can be used in the primer layer and the topcoat layer at the same time. One-sided coated samples were prepared on a small, single-station coater, as described in Example 2, except that two passes were required for each sample. In the first pass, the primer was applied to the adhesive side of Label-Lyte 196 LL B2 from ExxonMobil with the corona treater set at about 50% of its power output. As before, a 200-Quad cylinder was used to apply the coatings directly to the film samples (the gravure cylinder was moving the same direction as the web). After drying at 80°C, the roll was sent through the coater again with the topcoat being applied over the dried primer. No additional corona treatment was used on the second pass.

[0081] The final structure had the primer and topcoat on the coated side, with the uncoated print surface of Label-Lyte 196 LL B2 on the opposing surface, which has a surface energy that is greater than 40 dynes (as determined with a Poly Treat Check Pen™ from Independent Ink Inc.). Some adhesives anchor adequately to an uncoated surface that has been corona or flame treated. In this example, one-sided coated samples were pressed against the untreated coated surface (that is, in to out [I/O]) for one hour at an effective pressure of 750 psi (7500 lbs pressure applied to 10 in²) at 60°C. The blocking force was measured using a 90° T-peel test on an Instron. The same samples were also paired so that the coated surfaces were in contact with one another (that is, out to out [O/O]) and tested in the same way to estimate blocking tendencies of conceptual symmetrically coated structures.

[0082] All samples in this series had the same printable topcoat comprising 100 parts of the condensation polymer described in the comparative example, 100 parts Ludox™ CLP, 9.4 parts Tergitol™ 15S9 (0.05% of the total wet coating), and deionized water to yield a total solids content of 1.1%. The approximate coating weight was 0.031 g/m² after drying. Colloidal silica (Ludox™ CLP) is included in the topcoat formulation to help mitigate blocking to the opposite side of the film.

[0083] All primers in this series contained various concentrations of the condensation polymer described in the comparative example combined with 0.025% Tergitol 15S9 and 0.25% Hexyl Cellosolve in the wet coating to facilitate wetting of the substrate. Coating solids were set at 0.33%, 0.50%, 0.67%, and 1.0% solids to achieve the coating weights shown in Figure 5. It should be noted that when primers based on the condensation polymers were used, the coated films had much less color than the structures described in Example 3 that had Mica H760A as the primer. Including colloidal silica in the primer layer tends to diminish %INK-W; therefore, primers preferably do not contain significant amounts of colloidal silica or other materials that might compromise water resistance.

[0084] Figure 5 shows that increasing the thickness of the primer increased the undesirable blocking tendencies of the coated structure whether the surface opposite the print face is coated or just treated. Based on these results, one can conclude that a desirable coating weight for the primer is less than 0.020 g/m² and more preferably less than 0.015 g/m². (These thicknesses apply to primers, typically not to topcoats.) Moreover, blocking resistance is more robust if coatings of this invention are used on both sides of the film rather than just coating one side and treating the other (without coating). Nevertheless, useful one- or two-sided structures could be prepared with the coatings of this invention if the primer thickness was properly controlled.

Example 5. Other polyethyleneimines

[0085] This example shows that one can use other polyethyleneimine polymers to prepare useful condensation polymers. Two condensation polymers were prepared at 10% theoretical solids by mixing for greater than 24 hours with a Teflon coated magnetic stirring bar: Polymer 4A (of Table 4) comprising 57.0 g Mica H760A (11.7% solids, 100 parts), 13.33 g acetoacetoxyethyl methacrylate (200 parts), and 129.7 g deionized water and Polymer 4B comprising 6.7 g Epomin P1050 (50% solids, 100 parts, from Nippon Shokubai), 16.67 g acetoacetoxyethyl methacrylate (500 parts), and 176.7 g deionized water. Polymer 4A was a yellowish, somewhat translucent emulsion and Polymer 4B was an essentially colorless (whitish), translucent emulsion.

[0086] The emulsions were blended into the following coating formulations and coated on Label-Lyte 196 LL B2 from ExxonMobil as described in Example 4. All formulations contained 0.25% Hexyl Cellosolve to facilitate wetting of the substrate. The amount of Ludox CLP is based on 100 parts of the respective condensation polymer used in the formulation. Ink adhesion (%INK and %INK-W) were determined as described previously.

[0087] The above results show less than optimal results for retained ink adhesion after printed samples were immersed in water, because no primer was present beneath the printable topcoat. These results also show that condensation polymers based on Epomin PI 050 compare favorably in print performance to those created from Mica H760A.

[0088] Besides having less color, coatings based on Polymer 4B have the added advantage of having lower surface resistivity, which would enhance the ability of the coated film to dissipate static. Surface resistivity was measured at 50% RH, 24°C using a Keithley Model 8008 Resistivity Test Fixture attached to a Keithley Model 487 picoammeter/voltage source in which the applied voltage was set at 10.000 volts. The results appear in the following Table 5.

Example 6. Printable Structures Made from VOC-Free Condensation Polymers Formulated to Lower Coefficient of Friction and to Enhance Scuff Resistance

[0089] To aid in dispensing or stacking label face stocks, it is advantageous to control the coefficient of friction (COF) on the outside surface of the label. To maintain an attractive appearance, it is also desirable to have a coated surface that is resistant to scratching and scuffing and solvents such as isopropyl alcohol. Using waxes and particulates in coating formulations to accomplish this in addition to block resistance is well known in the art. It is far more difficult, however, to create a scuff-resistant and chemically-resistant structure that is still receptive to print inks. [0090] Primed samples were created for this example as described in Example 4. The primer for all three topcoats described in this example contained 100 parts of the condensation polymer made in Blend 26 (Table 1) formulated with 15 parts Tergitol 15S9 and diluted to a total solids content of 0.33%. This formulation is substantially free of VOCs.

[0091] Topcoat 6-1 : This VOC-free coating comprised 100 parts of Blend 26 (Mica- GMA, Table 1), 100 parts colloidal silica (Ludox CLP), 10 parts Surfynol 440 (Air Products, Allentown, PA), and diluted with deionized water to a total solids content of 1.1%. This material was applied over the primed film and dried as described in Example 4.

[0092] Topcoat 6-2: This VOC-free coating comprised 100 parts of Blend 26, 100 parts oxidized high-density polyethylene (MichemEmulsion 91240G.E from Michelman, Inc., Aubange, Belgium), 10 parts Tergitol 15S9, and diluted with deionized water to 1.1% solids.

[0093] Topcoat 6-3: This VOC-free coating contained 100 parts of Blend 19 (Mica- AAEM, Table 1), 100 parts oxidized HDPE (MichemEmulsion 91240G.E), 10 parts Tergitol 15S9, and diluted with deionized water to 1.1% solids.

[0094] Kinetic COF was measured for each sample tested against itself (coated surface to coated surface) using a slip/peel tester equipped with a 200g sled (Model #32-06 from Testing Machines, Inc., Amityville, NY).

[0095] Twenty one-way strokes with the smooth edge of a nickel were made by hand to scuff a 2-inch by 2-inch square on the coated samples. Haze values were measured in scuffed and unscuffed areas of the same sample with a Byk-Gardner Haze-gard Plus. Table 6 shows the results:

Table 6

[0096] Table 6 shows that oxidized HDPE is preferable to colloidal silica for improving scuff resistance. One can also see that changing the chemical nature of the amine-reactive modifying agent can also have an appreciable impact on scuff resistance. It is not obvious why AAEM should be preferred over GMA. As shown in Table 1, the ARE values were essentially the same for Blend 19 and Blend 26 and the same PAI (Mica H760A) was used in both blends. All three coated films were judged to be chemically resistant after rubbing the coated surfaces with an alcohol swab saturated with 70% isopropyl alcohol made by Becton Dickinson Consumer Products, Franklin Lakes, NJ. Haze is tested per ASTM D 1003.

[0097] Coated samples were printed by taping individual sheets to a continuous web that was being printed at 150 feet/minute on a Roto-8- 1 printing press that was set up in the following way:

• Station 1 : Not in use

• Station 2: Contained Pharmaflex Black UV-flexo ink from Water Ink Technologies applied with a 1400 lpi anilox roll that yielded a 1.21 ink density.

• Station 3: Not in use

• Station 4: Not in use

• Station 5: Contained Pharmaflex Cyan UV-flexo ink from Water Ink Technologies applied with a 1400 lpi anilox roll that yielded a 1.19 ink density.

· Station 6: Contained Pharmaflex Magenta UV-flexo ink from Water Ink

Technologies applied with a 1400 lpi anilox roll that yielded a 1.42 ink density.

• Station 7: Contained Pharmaflex Yellow UV-flexo ink from Water Ink Technologies applied with a 1400 lpi anilox roll that yielded a 0.95 ink density.

• Station 8: Not in use

[0098] %INK and %INK-W were measured for all samples. For magenta, cyan, and yellow, all values were 100%. For the black ink, all values were > 99%, which shows that condensation polymers from this invention can be formulated with low COF and improved scuff resistance with compromising printability.

Example 7. Low molecular weight PAI-based coating.

[0099] Example 7 demonstrates the advantages of lower molecular weight PAIs.

[00100] The following Table 7 shows the formulations for PAI condensation polymers prepared at 10% theoretical solids having different molecular weights.

Table 7. PAI t es, cross-linked and non-cross-linked

[00101] An emulsion of each commercial polymer in Table 7 was prepared by dissolving the particular grade of poly(ethyleneimine) completely in deionized water. Epomin P1050 was purchased from Nippon Shokubai, and Lupasol P was purchased from BASF. The weight average molecular weights in Table 7 are in "amu". Once dissolved, AAEM was added while the PEI solution was being stirred. In some cases (7-CP2 and 7-CP4), PETA (pentaerythritol triacrylate) was added as a cross-linker about one hour after the AAEM was added. The mixtures were stirred for at least 24 hours after the AAEM was added.

[00102] Using the polymers in Table 7, coatings were formulated and applied to films as in Example 3 to create symmetrically coated clear structures on the 26-inch wide coater, followed by slitting, and conditioning in a tropical environment, as described in Example 3. As indicated in the Table 8, two different primer formulations were used to create samples for this example that were based on the condensation polymers described above.

Table 8. Primer compositions

[00103] Topcoats were applied to the primed surface using a 550-lpi ceramic gravure cylinder using a combination of dilution and gravure-speed adjustments to achieve the indicated coating weights. All coatings contained 0.03% Tergitol 15S9 to ensure that the topcoat completely wet out the primed surface. The resulting coated films are summarized in Table 9.

Table 9. Coated Films

[00104] Blocking tendencies of the coated films were evaluated in two ways. The one- hour test is quantitative. Opposite surfaces of the symmetrically coated samples were pressed together in a Carver Press for one hour with an effective pressure on the blocked samples of 750 psi at a temperature of 60°C. After removing the pressure, the samples were mounted in an Instron and peeled at 5-inches/min with the samples being held at -90° to the peel direction. The average peel force is recorded in grams/inch.

[00105] The second blocking method is qualitative, and is described in Example 3. In this case the slit rolls were conditioned for a full week at 50°C/50% RH before being unwound on the Dusenbery ribbon slitter at about 550 feet/min. An acceptable result for the in-roll blocking test is to have the sample unwind all the way down to the core without tearing or without marring the appearance of the print surface, which usually occurs in the form of high or uneven haze.

[00106] The quantitative blocking results from the 1-hour blocking test in Table 10 show how the blocking values changed as a function of molecular weight variations in the PAI polymer and to changes in the level of cross-linker. The mean (of four trials) of the blocking value (g/inch, for 1 hr at 750 lbs/in²) is about 11 g/inch for films having inventive coating made from PAI having an M_w of 70,000 amu (this average includes samples with and without cross-linker), and the value is about 13.5 g/inch for films with inventive coatings made from PAI having an average M_w of 750,000 amu (also with and without cross-linker). Therefore, the main effect of increasing the molecular weight of the PAI was undesirable (increased blocking tendencies), regardless of whether or not a cross-linker was used. Likewise, the mean (of four trials) of the blocking value for cross-linked coatings on films was about 15 g/inch (which includes PAIs of high and low molecular weight), and was only about 8.5 for non-cross-linked coated films (again, this average includes PAIs with high and low molecular weight). Therefore, increasing the molecular weight by cross-linking, regardless of the initial molecular weight of the PAI, yielded poorer (increased) blocking values. Typically one would expect that higher molecular weight would improve block resistance. In summary, these data demonstrate the unexpected result that higher molecular weight, achieved either by polymerization or cross-linking, increased the blocking tendencies of the PAI condensation polymer.

[00107] Trends consistent with the above quantitative results were seen in the qualitative test, but the qualitative test gives a better idea of the practical importance of the above trends. The following Table 10 shows that with the proper molecular weight, symmetrically coated rolls can unwind acceptably, even after exposure to severe tropical conditions. The "XL" in the first column means that the PAI has been cross-linked as identified above in Table 7. However, if the molecular weight is too high, the unwinding properties become unacceptable. These results suggest that the preferred molecular weight for poly(ethyleneimine) used to make the condensation polymers disclosed in this invention is less than 100,000 amu. Since the condensation reaction presumably increases the molecular weight by the amount of the co-reactant used, then the preferred molecular weight for the condensation polymer is probably less than 600,000 amu if the PAI is poly(ethyleneimine) and the amine-reactive, ethenically unsaturated modifying agent is AAEM.

Table 10. Blocking studies for low molecular weight PAI

[00108] Having described the various features of the condensation product, polymer, and films having such coating thereon, provided herein in numbered embodiments is:

1. A composition comprising (or consisting essentially of, or consisting of) the condensation product of a polyalkylimine and one or more amine-reactive molecules comprising (or selected from the group consisting of) at least one of:

Rc₌c(_Ra)_(cx₂)_rC(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂ or (and)

Y-(CX₂)_m-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂

where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and selected from the group consisting of H and to C alkyl; R^c is selected from the group consisting of O and CX₂; each X can be the same or different and is selected from the group consisting of H, hydroxyl, halogen, and any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is selected from the group consisting of O and NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

The composition of embodiment 1, wherein R^c is oxygen (O); R^a and R^b is methyl or H; X and R^d is hydrogen (H); j is 1 ; k is 0; q is 2; p is 1 ; and A is oxygen (O).

The composition of embodiments 1 or 2, wherein Y is a three-membered oxirane ring (CH₂(0)CH₂); m is 1 ; p is 0; A is oxygen (O); R^b is methyl (CH₃); and X is hydrogen

(H).

The composition of any one of the previous embodiments, wherein from 0.1 or 0.2 to 0.6 or 0.8 or 1.0 or 1.1 or 1.2 or 2.0 or 2.5 or 3.0 amine-reactive equivalents ("ARE") is combined with the polyalkylimine.

The composition of any one of the previous embodiments, wherein the product is isolated from an aqueous diluent in solution at a pH of at least 8.

The composition of any one of the previous embodiments, wherein the amine-reactive molecule is selected from the group consisting of acetoacetoxyethyl methacrylate, methyl acetoacetonate, ethyl acetoacetonate, glycidyl methacrylate, methyl acrylate, acrylamide, acrylonitrile, 1 ,6-hexanediol diacrylate, 2 -hydroxy ethyl acrylate, trimethylpropane triacrylate, pentaerythritol triacrylate, and mixtures thereof.

The composition of any one of the previous embodiments, wherein the polyalkylimine comprises C₂ to CIQ alkyl or alkenyl-derived units.

The composition of any one of the previous embodiments, wherein the polyalkylimine consists of C₂ to CIQ alkyl or alkenyl-derived units, and imine-derived units.

The composition of any one of the previous embodiments, wherein the polyalkylimine is selected from the group consisting of polyethyleneimine, polypropyleneimine, polypropyl-co-ethyleneimine, and mixtures thereof.

The composition of any one of the previous embodiments, wherein styrenic moieties are absent from the polyalkylimine.

The composition of any one of the previous embodiments, wherein the polyalkylimine has a weight average molecular weight of from 3,000 or 5,000 or 10,000 or 20,000 or 40,000 to 80,000 or 100,000 or 150,000 or 200,000 or 300,000 or 500,000 or 1,000,000 or 2,000,000 amu. The composition of any one of the previous embodiments, wherein the composition is a suspension having a solids content within the range of from 0.1% or 0.5% or 1% to 3% or 4% or 5% or 8% or 10% or 30% or 50% or 60%, by weight of the coating. A film comprising at least one polymer layer having a first and second side, further comprising the coating of any of the previous embodiments on at least the first side, wherein the coating is the condensation product of a polyalkylimine and one or more amine-reactive molecules selected from the group consisting of at least one of:

Rc₌c(_Ra)_(cx₂)_rC(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂ and

Y-(CX₂)m-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂

where Y is a halogen or a three-membered oxirane ring; R^a and R^b are the same or different and selected from the group consisting of H and to C alkyl; R^c is selected from the group consisting of O and CX₂; each X can be the same or different and is selected from the group consisting of H, hydroxyl, halogen, and any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is selected from the group consisting of O and NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

The film of embodiment 13, wherein the first, second or both sides of the film are coated with the polyalkylimine condensation product.

The film of any one of embodiments 13- 14, wherein the film is a multi-layered film having outside surfaces on both sides of the film, wherein both of the outside surfaces are coated with the polyalkylimine condensation product.

The film of any one of embodiments 13- 15, wherein anti-blocking agents are substantially absent from the coating.

The film of any one of embodiments 13- 16, wherein the first side of the film has ink printed thereon, and the second side has adhesive adhered thereto.

The film of any one of embodiments 13- 17, wherein the polymer is selected from the group consisting of polyethylene, polypropylene, ethylene vinyl acrylate, nylon, polyester, and mixtures thereof.

The film of embodiment 18, wherein the polymer is polypropylene. The film of any one of embodiment 19, wherein the film comprises at least three layers, wherein a core layer comprises polypropylene, and at least one skin layer is adhered to the first and second sides of the core layer.

The film of any one of embodiments 19-20, wherein the polyalkylimine condensation product is coated on at least one skin layer.

The film of any one of the embodiments 19-21, further comprising a primer layer. The composition of any one of the preceding numbered embodiments, wherein the composition is free of volatile organic compounds.

A method of making the film of any one of the preceding embodiments comprising (or consisting essentially of, or most preferably, consisting of),

(a) combining in an aqueous medium a polyalkylimine and one or more amine- reactive molecules selected from the group comprising (or consisting of) at least one of:

_Rc₌c(_Ra)_(cx₂)_rC(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂

and

Y-(CX₂)_m-(0-[CR¾]_q)_p-A-C(0)-C(Rb)=CX₂

where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and selected from the group consisting of H and to alkyl; R^c is selected from the group consisting of O and CX₂; each X can be the same or different and is selected from the group consisting of H, hydroxyl, halogen, and any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is selected from the group consisting of O and NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive; and

(b) applying the reaction product, without separation or purification, to at least one surface of a film.

Also provided is the use of the composition of any one of the previous numbered embodiments as a coating on a printable film layer for a pressure sensitive label. Also provided is the use of the film of any one of the previous numbered embodiments in a pressure sensitive label.

Claims

A film comprising at least one polymer layer having a first and second side, further comprising a coating on at least the first side, wherein the coating is the condensation product of a polyalkylimine and one or more amine-reactive molecules comprising at least one of:

Rc₌c(_Ra)_(cx₂)_j-C(0)-(CX₂)_k-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂ or

Y-(CX₂)_m-(0-[CRd₂]_q)_p-A-C(0)-C(Rb)=CX₂

where Y is halogen or a three-membered oxirane ring; R^a and R^b are the same or different and are H or a C_j to alkyl; R^c is O or CX₂; each X can be the same or different and is H, hydroxyl, halogen, or any organic radical containing at least one carbon atom, wherein each R^d can be the same or different; A is O or NR^d; CR^d and CR^d ₂ can each be a separate moiety or a portion of a cyclic structure; j, k, and m are integers ranging from 0 to 6, inclusive; q is an integer ranging from 1 to 6, inclusive; and p is an integer ranging from 0 to 30, inclusive.

The film of claim 1, wherein the first and second sides of the film are coated with the polyalkylimine condensation product.

The film of claim 1, wherein the film is a multi-layered film having outside surfaces on both sides of the film, wherein both of the outside surfaces are coated with the polyalkylimine condensation product.

The film of claim 1, wherein anti-blocking agents are substantially absent from the coating.

The film of claim 1 , wherein the first side of the film has ink printed thereon, and the second side has adhesive adhered thereto.

The film of claim 1, wherein the polymer is at least one of polyethylene, polypropylene, ethylene vinyl acrylate, nylon, polyester, or mixtures thereof.

7. The film of claim 6, wherein the film comprises at least three layers, wherein a core layer comprises polypropylene, and at least one skin layer is adhered to the first and second sides of the core layer. 8. The film of claim 6, wherein the polyalkylimine condensation product is coated on at least one skin layer.

9. The film of claim 6, wherein the coating weight is less than 0.30 g/m². 10. The film of claim 1, wherein the coating has a solids content within the range of from 0.1% to 60%, by weight of the coating.

11. The film of claim 1, wherein the coating comprises from 1% to 50 wt% anti-block by weight of the coating composition.

12. The film of claim 1, wherein the polyalkylimine has a weight average molecular weight of from 3,000 to 2,000,000 amu.

13. The film of claim 11, wherein the anti-block is oxidation treatment of the skin surface.

14. The film of claim 1, wherein styrenic moieties are absent from the polyalkylimine.

15. The film of claim 1, further comprising a primer layer between the film and the coating, the primer layer comprising a polyalkylamine having a weight average molecular weight of from 20,000 to 80,000 or 100,000 or 150,000 or 200,000 or

500,000 amu and also comprising from 2 to 20 parts of a non-ionic surfactant.

16. The film of claim 1, wherein from 0.1 or 0.2 to 0.6 or 0.8 or 1.0 or 1.1 or 1.2 or 2.0 or 2.5 or 3.0 amine-reactive equivalents ("ARE") of amine-reactive molecules are combined with the polyalkylimine.

17. The film of claim 1, wherein the condensation product is isolated from an aqueous diluent in solution at a pH of at least 8 prior to coating the film.

18. The film of claim 1, wherein the amine-reactive molecule is selected from the group consisting of acetoacetoxyethyl methacrylate, methyl acetoacetonate, ethyl acetoacetonate, glycidyl methacrylate, methyl acrylate, acrylamide, acrylonitrile, 1,6- hexanediol diacrylate, 2-hydroxyethyl acrylate, trimethylpropane triacrylate, pentaerythritol triacrylate, and mixtures thereof.

19. A label comprising the film of claim 1.