Hyperbranched polyesters in printing inks

Abstract

The invention relates to multilayer materials for producing packaging comprising at least two films and also a layer which is printed with a packaging printing ink, said packaging printing ink comprising a certain hyperbranched polyester containing functional groups. The invention further relates to a packaging printing ink which comprises a certain hyperbranched polyester containing functional groups, and to the use of said printing ink for producing multilayer materials.

Claims

1. A multilayer material comprising: a first film comprising a polymeric material; at least one print layer comprising a packaging printing ink; and a second film; wherein: the packaging printing ink comprises 5 wt % to 35 wt % of a binder, based on the sum of all constituents in the packaging printing ink, wherein the binder comprises a first binder and a second binder; the first binder comprises at least one hyperbranched polyester containing functional groups selected from the group consisting of OH, COOH and COOR groups, wherein R comprises groups having from 1 to 60 carbon atoms and optionally may also contain heteroatoms or further substituents; the hyperbranched polyester comprises the polymerization product of:  at least one acid selected from the group consisting of 1,2-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, and 1,4-cyclohexane dicarboxylic acid or anhydrides thereof; and  at least one at least trivalent aliphatic alcohol selected from the group consisting of trimethylolpropane, glycerol, and pentaerythritol; wherein:  the at least trivalent aliphatic alcohol hydroxyl groups to the acid carboxyl groups have a ratio of 2:1 to 1:2; and  the hyperbranched polyester has a number average molecular weight of 300 g/mol to 10,000 g/mol, a weight average molecular weight to number average molecular weight ratio of about 1.3:1 to 5:1, and a glass transition temperature of from 30° C. to 50° C.; the second binder comprises nitrocellulose; and a weight ratio of the hyperbranched polyester to the total amount of all the binders is greater than 50% by weight and less than 80% by weight, and wherein the package printing ink further comprises about 40% by weight to about 80% by weight of at least one solvent.

2. The multilayer material of claim 1, wherein the first film is selected from the group consisting of polyethylene, polypropylene, polystyrene, polyester and polyamide.

3. The multilayer material of claim 1, wherein the second film is selected from the group consisting of polyethylene, polypropylene, polystyrene, polyester, polyamide and aluminum.

4. The multilayer material of claim 1, wherein the at least one acid is 1,2-cyclohexane dicarboxylic acid or 1,2-cyclohexane dicarboxylic acid anhydride.

5. The multilayer material of claim 1, wherein the trivalent aliphatic alcohol is trimethylolpropane.

6. A printing ink comprising: 5 wt % to 35 wt % of a binder, based on the sum of all constituents in the printing ink, wherein the binder comprises a first binder and a second binder; and at least one solvent; wherein: the first binder comprises at least one hyperbranched polyester, the hyperbranched polyester comprises the polymerization product of: at least one acid selected from the group consisting of 1,2-cyclohexane dicarboxylic acid, 1,3-cyclohexane dicarboxylic acid, and 1,4-cyclohexane dicarboxylic acid or anhydrides thereof; and at least one at least trivalent aliphatic alcohol selected from the group consisting of trimethylolpropane, glycerol, and pentaerythritol; wherein: the at least trivalent aliphatic alcohol hydroxyl groups to the acid carboxyl groups have a ratio of 2:1 to 1:2; and the hyperbranched polyester has a number average molecular weight of 300 g/mol to p10,000 g/mol, a weight average molecular weight to number average molecular weight ratio of about 1.3:1 to 5:1, and a glass transition temperature of from 30° C. to 50° C.; the second binder comprises nitrocellulose; and a weight ratio of the hyperbranched polyester to a total amount of all the binders is greater than 50% by weight and less than 80% by weight, and wherein the printing ink comprises about 40% by weight to about 80% by weight of the at least one solvent.

7. The printing ink of claim 6 further comprising at least one colorant.

8. The printing ink of claim 7, wherein the colorant comprises titanium dioxide, iron oxide, an interference pigment, carbon black, a metal powder, an azo pigment, a phthalocyanine pigment, an isoindoline pigment.

9. The printing in of claim 7, wherein the colorant comprises phthalocyanine blue 15:4, phthalocyanine green 7, green 36, yellow 12, yellow 14, red 57:1, or red 52:1.

10. The printing ink of claim 6 further comprising an additive selected from the group consisting of calcium carbonate, aluminum oxide hydrate, aluminum silicate, magnesium silicate, a wax, a fatty acid amide, a plasticizer, a dispersing agent, and an adhesion promoter.

11. The printing ink of claim 10, wherein the additive is present in the ink from 0 wt % to 20 wt %.

12. The printing ink of claim 6, wherein the at least one acid is 1,2-cyclohexane dicarboxylic acid or 1,2-cyclohexane dicarboxylic acid anhydride.

13. The printing ink of claim 6, wherein the trivalent aliphatic alcohol is trimethylolpropane.

Description

EXAMPLES

(1) General Procedure

(2) Molecular weights were determined by gel permeation chromatography (GPC);

(3) eluent: tetrahydrofuran (THF); reference material: PMMA.

(4) Acid values (AN) were determined according to previous DIN 53402.

(5) Hydroxyl values (OH value) were determined according to DIN 53240, part 2.

(6) Glas transition temperatures (Tg) were measured using differential scanning calorimetry (DSC). During the measurement, samples were cooled down to a starting temperature approximately 50° C. below the T.sub.g expected and then heated up to a final temperature approximately 50° C. above the T.sub.g expected with a rate of 10° C./min. The given Tg represents the result of the second heating cycle.

(7) DBTL=dibutyl tin dilaurate

(8) TMP=trimethylolpropane

(9) HPAA=1,2-cyclohexane dicarboxylic anhydride (CAS 85-42-7)

(10) Synthesis of Hyperbranched Polyesters

Comparative Example 1

(Analogous to Product of Example 1 of US 2005/0147834 A1)

(11) In a 2 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 680 g (4.65 mol) of adipic acid, and 520 g (3.88 mol) TMP were placed. 0.36 g DBTL were added as a catalyst and the reaction mixture was heated to 160° C. upon stirring. The mixture was stirred at 160° C. for 3 h and reaction water was collected. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 87 mg KOH/g polymer was reached.

(12) The product was obtained as colorless resin. AN=87 mg KOH/g polymer, OH value=226 mg KOH/g polymer, M.sub.n=2200 g/mol, M.sub.W=13100 g/mol, Tg=−30° C.

Comparative Example 2

(Analogous to Product of Example 2 of US 2005/0147834 A1)

(13) In a 2 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 680 g (4.65 mol) of adipic acid, and 520 g (3.88 mol) TMP were placed. 0.36 g DBTL were added as a catalyst and the reaction mixture was heated to 160° C. upon stirring. The mixture was stirred at 160° C. for 4 h and reaction water was collected. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 100 mg KOH/g polymer was reached.

(14) The product was obtained as colorless resin. AN=100 mg KOH/g polymer, OH value=215 mg KOH/g polymer, M.sub.n=1100 g/mol, M.sub.w=4900 g/mol, Tg=−31° C.

Comparative Example 3

(Analogous to Product of Example 12 of US 2007/213501 A1)

(15) In a 2 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 742 g (5.10 mol) of adipic acid, 257 g (2.80 mol) glycerol, and 201 g (1.40 mol) 1,4-dimethylol-cyclohexane were placed. 0.6 g DBTL were added as catalyst and the reaction mixture was heated to 160° C. upon stirring. The mixture was stirred at 160° C. for 8 h and reaction water was collected. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 95 mg KOH/g polymer was reached.

(16) The product was obtained as colorless resin. AN=95 mg KOH/g polymer, OH value=151 mg KOH/g polymer, M.sub.n=1920 g/mol, M.sub.W=10220 g/mol, Tg<−35° C.

Example 4

(17) In a 2 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 580 g (3.76 mol) of HPAA, and 420 g (3.13 mol) TMP were placed. 0.3 g DBTL were added as catalyst and the reaction mixture was heated to 160° C. upon stirring. The mixture was stirred at 180° C. for 6 h and reaction water was collected. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 92 mg KOH/g polymer was reached.

(18) The product was obtained as colorless brittle solid. AN=92 mg KOH/g polymer, OH value=187 mg KOH/g polymer, M.sub.n=500 g/mol, M.sub.W=2200 g/mol, Tg=44° C.

Example 5

(19) In a 1 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 348 g (2.26 mol) of HPAA, and 252 g (1.88 mol) TMP were placed and heated to 180° C. for 5.5 h and reaction water was removed during that time. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 93 mg KOH/g polymer was reached.

(20) The product was obtained as colorless brittle solid. AN=92 mg KOH/g polymer, OH value=191 mg KOH/g polymer, M.sub.n=740 g/mol, M.sub.w=2400 g/mol, Tg=35° C.

Example 6

(21) In a 2 liter round bottom flask equipped with mechanical stirrer, thermometer, gas inlet and distillation apparatus with collecting flask, 551 g (3.7 mol) of 1,2-phtalic acid anhydride, and 500 g (3.7 mol) TMP were placed. 0.3 g DBTL were added as catalyst and the reaction mixture was heated to 180° C. upon stirring for 7 h and reaction water was collected. The reaction was followed by acid number and stopped by cooling down to ambient temperature when an acid number of 40 mg KOH/g polymer was reached.

(22) The product was obtained as yellow brittle solid. AN=36 mg KOH/g polymer, OH value=236 mg KOH/g polymer, M.sub.n=1590 g/mol, M.sub.w=6530 g/mol, Tg=44° C.

(23) A number of flexographic printing inks were prepared by mixing nitrocellulose based color dispersions with the aforementioned procedure examples.

(24) Ink Formulation and Testing: ink typically is made by mixing a color dispersion which contains colorants, dispersing resins, dispersing additives and solvents, with letdown vehicles which are composed of polymer binders, additives, and solvents.

(25) Color dispersions were prepared by grinding pigments with the Lau™ Disperser DAS H 200-K paint shaker using glass beads with 2 mm diameter as grinding media. Below are typical dispersion formulations used for white and color inks.

(26) TABLE-US-00001 Dispersion White Color Composition dispersion dispersion Pigment Titanium oxide Blue 15:4 % Pigment 56%   26% % Dispersant  7%  7.5% Solvents 37% 66.5% n-Propanol/n-Propyl acetate 80/20

(27) Titanium oxide used in the invention was Kemari RODI. Phthalocyanine blue 15:4 was Toyo blue 7400G

(28) The letdown vehicle was prepared using the hyperbranched polyester samples as listed in the aforementioned examples by dissolving at least 50% but no greater than 75% by weight of hyperbranched polyesters in a standard solvent, typically n-propanol. The base inks were obtained by mixing color dispersion with letdown vehicles at a standard ratio with appropriate amount of solvent. The base ink viscosity of the base inks were measured using Brookfield (ASTM D2196) then it was adjusted close to 100 mPas print viscosity at 25° C. for flexographic printing with solvent mix. The finish ink compositions (by weight %) at print viscosity are summarized for white and blue inks in the tables below. All examples were soluble in n-propanol and made stable inks, except those polyesters according to example-1, -2, and -3. Inks made with polyesters from example-1, -2, and -3 exhibited phase separation on standing at 25° C. for 24 hours. Control ink was made of polyurethane NeoRez® U335 ink vehicle. NeoRez® U335, available from DSM NeoResins Inc., Wilmington, is a non-reactive high molecular weight semialiphathic polyurethane recommended in flexo and for gravure printing ink formulations.

(29) TABLE-US-00002 TABLE 1 Ink composition of white inks Sample no. TiO2 Nitrocellulose Binder Solvent Sum Example-4 35.2 4.4 11.8 48.6 100 Example-5 36.9 4.6 12.3 46.2 100 Example-6 34.5 4.3 11.6 49.6 100 Control 29.0 3.6 9.7 57.7 100

(30) TABLE-US-00003 TABLE 2 Ink composition of blue inks Sample no. Blue 15:4 Nitrocellulose Binder Solvent Sum Example-4 19.3 4.8 11.9 64.0 100 Example-5 19.4 4.9 12.0 63.7 100 Example-6 18.7 4.7 11.6 65.0 100 Control 16.2 4.0 10.0 69.8 100

(31) Inks were drawn down on a PET film (Dupont™48LBT) with 42 dyne/cm surface tension using a K-Coater (from RK Print-Coat Instruments Ltd) and K-1 rod with 0.08 mm wire diameter giving 6 micron-meter wet film deposit.

(32) Following test protocols were used to determine physical properties of printed film.

(33) Tape Adhesion Test

(34) A popular practice to check ink adhesion on a printed film in the printing industry is tape adhesion (ASTM F 2252-03). Measurements were conducted after ink drawn down for one hour at room temperature to make sure solvent was completely evaporated. Results were rated in 1-5 scale; 5 as no ink pulled off from the film and 1 as 100% pulled off from the film.

(35) Blocking Resistance

(36) Blocking resistance is measured by using a spring loaded press, K53000 I.C. block tester, from Koehler Instrument. This test is to emulate a roll of printed film that is under storage conditions with heat and pressure. The blocking test is set at 10 psi, 50° C. for 16 hours. The rating was in 1-5 scale ; 5 as the best with no ink peel off 1 as 100% pulled off from the film.

(37) Peel Strength of Lamination

(38) A critical performance for a lamination ink is the ability to form an integral laminate with an aid of adhesive which is bonding a printed film with a sealant film which is normally polyolefin film with a lower melting point such as LDPE, low density polyethylene. Tycel™ UR7975/UR6029 (from Liofol Corporation) was used as adhesive. Bond Strength of lamination samples was evaluated by Instron™, a tensile tester. The most common configuration is a standard T-peel, which involves pulling apart two strips of substrate that have been adhered together resulting in a “T” formation (ASTM D1876).

(39) Typical peel force measurement is conducted at a constant peel rate between 1 to 20 inches per minute, preferably 6 to 15 inches per minute. The threshold for the bond strength is the minimal force to tear the packaging film. A destructive bond strength is always preferred. A typical lamination packaging the threshold is about 135 gram-force per liner centimeter. Bond strength measurement beyond 135 gm/cm is the minimum force to achieve destructive bond strength.

(40) Ink performance of white and blue inks are summarized in Table 3 and 4.

(41) TABLE-US-00004 TABLE 3 Ink performance of white inks Blocking: Sample no. Tape adhesion face/back Film Tear Example-4 5 5 yes Example-5 5 5 yes Example-6 5 5 yes control 5 5 yes

(42) TABLE-US-00005 TABLE 4 Ink performance of blue inks Blocking: Sample no. Tape adhesion face/back Film Tear Example-4 5 5 yes Example-5 5 5 yes Example-6 5 5 yes Control 5 5 yes

(43) The embodiments, illustratively described herein may suitably be practiced in the absence of any element or elements, limitation or limitations, not specifically disclosed herein. Thus, for example, the terms ‘comprising,’ ‘including,’ ‘containing,’ etc. shall be read expansively and without limitation. Additionally, the terms and expressions employed herein have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of the features shown and described or portions thereof, but it is recognized that various modifications are possible within the scope of the claimed technology. Additionally, the phrase ‘consisting essentially of’ will be understood to include those elements specifically recited and those additional elements that do not materially affect the basic and novel characteristics of the claimed technology. The phrase ‘consisting of’ excludes any element not specified.

(44) All publications, patent applications, issued patents, and other documents referred to in this specification are herein incorporated by reference as if each individual publication, patent application, issued patent, or other document was specifically and individually indicated to be incorporated by reference in its entirety. Definitions that are contained in text incorporated by reference are excluded to the extent that they contradict definitions in this disclosure.

(45) The present disclosure is not to be limited in terms of the particular embodiments described in this application, which are intended as illustrations of various aspects. Many modifications and variations can be made without departing from its spirit and scope, as will be apparent to those skilled in the art. Functionally equivalent compositions, apparatuses, and methods within the scope of the disclosure, in addition to those enumerated herein, will be apparent to those skilled in the art from the foregoing descriptions. Such modifications and variations are intended to fall within the scope of the appended claims. The present disclosure is to be limited only by the terms of the appended claims, along with the full scope of equivalents to which such claims are entitled. It is to be understood that this disclosure is not limited to particular methods, reagents, compounds compositions or biological systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

(46) In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

(47) As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges disclosed herein also encompass any and all possible subranges and combinations of subranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as ‘up to,’ ‘at least,’ ‘greater than,’ ‘less than,’ and the like, include the number recited and refer to ranges which can be subsequently broken down into subranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member.

(48) While certain embodiments have been illustrated and described, it should be understood that changes and modifications can be made therein in accordance with ordinary skill in the art without departing from the technology in its broader aspects as defined in the following claims.