A rosin polymer to be used as inert component in a coating, in particular a radiation curing coating such as a radiation curing printing ink

Abstract

A polymer is obtainable by a method comprising the reaction of: a) at least one rosin acid containing at least two conjugated carbon-carbon double bonds, b) at least one polydienophile compound comprising two or more carbon-carbon double bonds, c) at least one compound selected from the group consisting of polyhydroxyl compounds c.sub.1), polyepoxy compounds c.sub.2), polyamine compounds c.sub.3), polythiol compounds c.sub.4) and arbitrary combinations of two or more of the aforementioned compounds and d) at least one photoinitiator d.sub.1) and/or at least one co-initiator d.sub.2), wherein the at least one photoinitiator d.sub.1) and/or the at least one co-initiator d.sub.2) comprises at least one functional group being selected from the group of ester groups, carboxylic acid groups, carboxylic acid chloride groups, carboxylic acid anhydride groups, hydroxyl groups, thiol groups, primary amine groups, halogen groups, epoxy groups, isocyanate groups, isothiocyanate groups and arbitrary combinations of two or more of the aforementioned groups.

Claims

1. A polymer being obtainable by a method comprising the reaction of: a) at least one rosin acid containing at least two conjugated carbon-carbon double bonds, b) at least one polydienophile compound comprising two or more carbon-carbon double bonds, c) at least one compound selected from the group consisting of polyhydroxyl compounds c.sub.1), polyepoxy compounds c.sub.2), polyamine compounds c.sub.3), polythiol compounds c.sub.4) and arbitrary combinations of two or more of the aforementioned compounds and d) at least one photoinitiator d.sub.1) and/or at least one co-initiator d.sub.2), wherein the at least one photoinitiator d.sub.1) and/or the at least one co-initiator d.sub.2) comprises at least one functional group being selected from the group of ester groups, carboxylic acid groups, carboxylic acid chloride groups, carboxylic acid anhydride groups, hydroxyl groups, thiol groups, primary amine groups, halogen groups, epoxy groups, isocyanate groups, isothiocyanate groups and arbitrary combinations of two or more of the aforementioned groups.

2. The polymer in accordance with claim 1, wherein the polymer does not contain any terminal carbon-carbon double bond.

3. The polymer in accordance with claim 1, wherein in the method also at least one carboxylic acid or carboxylic acid derivative e) comprising one or more carboxylic acid groups, carboxylic acid chloride groups or carboxylic acid anhydride groups is reacted with components a) to d).

4. The polymer in accordance with claim 1, wherein the at least one rosin acid a) is selected from the group consisting of pimaric acid, neoabietic acid, palustric acid, abietic acid, levopimaric acid and arbitrary combinations of two or more of the aforementioned carboxylic acids.

5. The polymer in accordance with claim 1, wherein the at least one polydienophile compound b) comprising two or more double bonds is a compound according to the following general formula (1): ##STR00033## wherein R.sub.1 to R.sub.3 and R.sub.3 to R.sub.7 are independently from each other selected from the group consisting of hydrogen, alkyl groups, substituted alkyl groups, aromatic groups, substituted aromatic groups, heterocyclic groups, substituted heterocyclic groups, cycloaliphatic groups and substituted cycloaliphatic groups, wherein the substituted group may be substituted with one or more ether groups, one or more ester groups, one or more carboxylic groups, expoxy groups, one or more amide groups, or the like, with R.sub.1 or R.sub.2 being optionally a bond with R.sub.3 and/or R.sub.6 or with R.sub.7 being optionally a bond with R.sub.5, R.sub.4 is an alkyl group or a substituted alkyl group, wherein the substituted alkyl group may be substituted with one or more ether groups, one or more ester groups, one or more carboxylic groups, one or more hydroxyl groups, one or more epoxy groups, one or more amide groups, one or more urethane groups, one or more thiol groups, one or more acid chloride groups, one or more keto or aldehyde groups, and k.sub.1 and k.sub.2 are independently from each other an integer of 0 to 20 and preferably of 2 to 20.

6. The polymer in accordance with claim 1, wherein the at least one polydienophile compound b) comprising two or more double bonds is selected from the group of diacrylate compounds, triacrylate compounds, tetraacrylate compounds, penta- or higher functional acrylate compounds, dimethacrylate compounds, trimethacrylate compounds, tetramethacrylate compounds, penta- or higher functional methacrylate compounds, itaconic compounds, and arbitrary combinations of two or more of the aforementioned compounds, wherein the polydienophile compound b) preferably has a weight average molecular weight M.sub.w determined by gel permeation chromatography of 200 to 5,000 g/mol.

7. The polymer in accordance with claim 1, wherein the at least one polyhydroxyl compound c.sub.1) is a monomeric polyol with two or more hydroxyl groups, a linear polyetherpolyol with two or more hydroxyl groups, a branched polyetherpolyol with two or more hydroxyl groups, a sugar alcohol with three or more hydroxyl groups or a triglyceride with two or three secondary hydroxyl groups, and preferably a compound being selected from the group consisting of 1,2,4-butanetriol, 1,2,6-hexanetriol, 3-methyl-pentane-1,3,5-triol, diglycerin, dipentaerythritol, ditrimethylol propane, erythritol, fucitol, galactitol, glycerin, hydroxymethyl hexanediol, iditol, inositol, lactitol, maltitol, maltotetraitol, maltotriitol, mannitol, pentaerythritol, polyglycitol, ribitol, threitol, arabitol, trimethylol butane, trimethylol ethane, trimethylol hexane, trimethylol octane, trimethylol propane, tripentaerythritol, volemitol, tris (2-hydroxyethyl) isocyanurate, neopentyl glycol, ethylene glycol, diethylene glycol, propylene glycol, methylpropanediol, polyether polyols, ethoxylated or propoxylated branched polyols, sorbitol, xylitol, isosorbide and arbitrary combinations of two or more of the aforementioned polyhydroxyl compounds.

8. The polymer in accordance with claim 1, wherein the at least one polyepoxy compound c.sub.2) comprises at least two epoxy groups and is selected from the group consisting of polyglycidylethers, bisphenol A diglycidylether, bisphenol F diglycidylether, ethoxylated/propoxylated bisphenol A diglycidylether, ethoxylated/propoxylated bisphenol F diglycidylether, 3,4-epoxycyclohexylmethyl-3,4-epoxy-cyclohexane carboxylate, epoxyphenol novolacs, 1,4-butanediol diglycidylether, neopentylglycol diglycidylether, 1,6-hexandiol diglycidylether, polyoxypropylenglycol diglycidylethers, trimethylolpropane triglycidylether, poly(tetramethylene oxide) diglycidylethers, polyglycerol-3-polyglycidylethers, glycerin triglycidylether, pentaerythrol polyglycidylether, polyglycidylether of ethoxylated trimethylolpropane, polyglycidylether of propoxylated glycerin, hydrated bisphenol A-diglycidylether, hydrated bisphenol F-diglycidylether, triglycidyl isocyanurate, novolac resins and arbitrary combinations of two or more of the aforementioned polyepoxy compounds.

9. The polymer in accordance with claim 1, wherein the at least one polyamine compound c.sub.3) comprises at least two amino groups and is selected from the group consisting of polyamines, alkoxylated polyamines, polyether amines, polyester amines, polyamido amines, amine terminated polyurea compoundsand arbitrary combinations of two or more of the aforementioned compounds, and is preferably selected from the group consisting of polypropylene glycol diamines, polyethylene glycol diamines, alkoxylated glycerol triamines, diethylene triamine, tetraethylene diamine, polytetramethylene glycol diamines, primary amines based on polyoxyalkyl polyamine with a weight average molecular weight preferably of 200 to 5,000 g/mol, N,N,N,N-tetraglycidyldiamino-4,4-diphenylmethane, isophorone diamine, cyanoethylated trimethyl-hexamethylenediamine, diaminodiphenylmethane and arbitrary combinations of two or more of the aforementioned compounds.

10. The polymer in accordance with claim 1, wherein the at least one polythiol compound c.sub.4) comprises at least two thiol groups and is selected from the group consisting of aliphatic polythiols, aromatic polythiols, ester polythiols, mercaptan terminated polymers and arbitrary combinations of two or more of the aforementioned compounds.

11. The polymer in accordance with claim 1, wherein the at least one photoinitiator d.sub.1) and/or at least one co-initiator d.sub.2) each comprise at least one functional group being selected from the group consisting of ester groups, carboxylic acid groups, carboxylic acid chloride groups, carboxylic acid anhydride groups, hydroxyl groups, thiol groups, primary amino groups, halogen groups, epoxy groups, isocyanate groups, isothiocyanate groups and arbitrary combinations of two or more of the aforementioned functional groups, wherein preferably the at least one photoinitiator d.sub.1) and/or at least one co-initiator d.sub.2) are selected from the group consisting of benzophenones, thioxanthones and tertiary amino compounds being functionalized with an aforementioned functional group.

12. The polymer in accordance with claim 1, wherein the at least one carboxylic acid or derivative comprising one or more carboxylic acid groups, carboxylic acid chloride groups or carboxylic acid anhydride groups e) is selected from the group consisting of 2-ethyl hexanoic acid, oleic acid, benzoic acid, tert-butyl benzoic acid, C.sub.1-20-monocarboxylic acids, 2,4,6-trimethylbenzoic acid, adipic acid, succinic acid, sebacic acid, C.sub.1-20-dicarboxylic acids, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, trimelithic acid, itaconic acid, glutaconic acid, traumatic acid, muconic acid, glutinic acid, citraconic acid, mesaconic acid and arbitrary combinations of two or more of the aforementioned compounds.

13. The polymer in accordance with claim 1, which fulfils one or more of the subsequent criteria: i) having a weight average molecular weight M.sub.w measured by gel permeation chromatography of 600 to 50,000 g/mol, preferably of 1,000 to 50,000 g/mol and more preferably of 4,000 to 30,000 g/mol, ii) having a number average molecular weight M.sub.n measured by gel permeation chromatography of 100 to 30,000 g/mol, preferably of 500 to 20,000 g/mol and more preferably of 700 to 10,000 g/mol, iii) having an acid number of 0 to 80 mg KOH/g, preferably of 0 to 50 mg KOH/g and more preferably of 1 to 20 mg KOH/g, iv) having a softening point of 40 to 200 C., preferably of 70 to 160 C. and more preferably of 80 to 150 C., v) having a viscosity when diluted in 50% dipropylene glycol diacrylate (DPGDA) of 1 to 300 Pa.Math.s, preferably of 1 to 200 Pa.Math.s and more preferably of 10 to 100 Pa.Math.s, measured with a cone-plate geometry, the cone having a diameter of 25 mm and an angle of 1, the gap of the cone and the plate being 0.05 mm, at 20 C. temperature and at a deformation rate of 50 radian/s.

14. A method for producing a polymer in accordance with claim 1, comprising reacting in one or more steps: a) at least one rosin acid containing at least two conjugated double bonds, b) at least one polydienophile compound comprising two or more double bonds, c) at least one compound selected from the group consisting of polyhydroxyl compounds c.sub.1), polyepoxy compounds c.sub.2), polyamine compounds c.sub.3), polythiol compounds c.sub.4) and arbitrary combinations of two or more of the aforementioned compounds and d) at least one photoinitiator d.sub.1) and/or at least one co-initiator d.sub.2), wherein the at least one photoinitiator d.sub.1) and/or the at least one co-initiator d.sub.2) comprises at least one functional group being selected from the group of ester groups, carboxylic acidgroups, carboxylic acid chloride groups, carboxylic acid anhydride groups, hydroxyl groups, thiol groups, primary amine groups, halogen groups, epoxy groups, isocyanate groups, isothiocyanate groups and arbitrary combinations of two or more of the aforementioned compounds.

15. A coating comprising: 1 to 50% by weight of the polymer in accordance with claim 1, 10 to 60% by weight of binder, 0 to 40% by weight of solvent, 0 to 40% by weight of pigment, 0 to 20% by weight of one or more fillers, 0 to 10% by weight of one or more additives and 0 to 10% by weight of one or more photoinitiators and/or co-initiators.

Description

IN THE FIGURES

[0246] FIG. 1 shows a sketch of the cross cut method. The projections of the edges A-D that bend upwards on the plane that shows out of the plane are displayed on the left hand side and the bottom of the figure. The figure is adapted from DIN norm 55403 (2014)

[0247] FIG. 2 shows photographs of the cross cut method applied to EWR 57 films coated with a 24 m thick layer of a coating formulations containing Comparative example 1, comparative example 2 and example 6 and cured under UV light.

[0248] The DIN norm 55403 describes a test to evaluate the tendency of plastic films or film composites to coil. When applied on plastic films, the shrinkage of the UV coating during the curing reaction causes an internal stress in the coating that leads to a coiling of the coated plastic film. A method was developed to determine the tendency of the sample to coil in analogy to the cross-cut method described in the DIN norm 55403, 2014. Therefore the edges of the coated plastic film have been fixed on a card board and a cross is cut into the sample subsequently after the curing step. As a result of the internal stress the edges of the cross-cut bend upwards or even start to coil. FIG. 1 shows a sketch of the cross-cut method applied to a coated plastic film. The projection of the upwards bending edges looking from the side on the sample is displayed on the lefthand side and on the buttom of the figure. The respective Edges A-D are marked in the projection and on the sketch. The distance between the four Edges A-D and the table was measured with help of a ruler and indicated in small letters a-d. For a good comparison of the samples the values a-d (unit was mm) were added to give the value L. The measured distances a-d decrease with time due to a relaxation of the internal stress in the coating. For that reason the distances were measured within 5 to 10 minutes after the curing reaction. For a better comparability each experiment was repeated three times. The relative error of the three repetitions was around 20% or lower. It is important that all coatings were fully cured and their surface was tack-free.

[0249] The results for L are summarized in Table 3 and FIG. 2 shows photographs of the samples 30 minutes after the curing reaction.

TABLE-US-00004 TABLE 3 Results employing the cross cut method to plastic films coated with coatings of comparative example 1, comparative example 2 and example 6 and two different film thicknesses of the coated layer. Comparative Comparative example 1 example 2 Example 6 Including CAB DAP Resin 2 Film thickness 12 m L.sup.[1] [mm] #1 85 54 6 L.sup.[1] [mm] #2 60 85 8 L.sup.[1] [mm] #3 57 55 6 Mean value [mm] 67 65 7 Rel. Error 19% 22% 14% Film thickness 24 m L.sup.[1] [mm] #1 160 130 24 L.sup.[1] [mm] #2 155 102 37 L.sup.[1] [mm] #3 140 145 38 Mean value [mm] 152 126 33 Rel. Error 6% 14% 19% .sup.[1]L = a + b + c + d

[0250] FIG. 1 and Table 3 demonstrate that for the coating formulated with Resin-2 (example 6) the curling of the edges is close to very low in comparison with the coatings formulated with CAB or DAP. It could be demonstrated that the internal stress and shrinkage in the UV cured coating layer could be significantly reduced using Resin-2 in comparison with a CAB and a DAP resin.