Primer composition

Abstract

The present invention relates to a primer composition comprising one or more of a monofunctional or multifunctional radiation curable monomer having a molecular weight of less than 1000 Dalton or a mixture thereof, a photo initiator, an inert resin, and an oligomer having a molecular weight of 1000 Dalton or more. The composition is characterized in that it additionally comprises at least one chemically unmodified polysaccharide, whereby the polysaccharide may be hydrolyzed to adjust its chain length, but has not been chemically modified through esterification, etherification, oxidation, or substitution of its functional groups and wherein reductions in chain length are achieved by hydrolysis of glycosidic linkages to reduce chain length without introducing substituents or altering the repeating sugar units.

Description

[0001] Primer composition

[0002] The present invention relates to a primer composition exhibiting excellent deinking properties.

[0003] Plastic packaging is extensively utilized and marketed for a variety of products, ranging from food and beverages to electronics, pharmaceuticals, detergents, and numerous other items. Its popularity can be attributed to several beneficial properties, including lightweight nature, energy-efficient production processes, excellent printability, and effective barrier characteristics. However, despite these advantages, plastic packaging contributes significantly to waste generation. In the absence of an effective waste management system, this can lead to substantial pollution in landfills.

[0004] The situation can be improved through effective collection and sorting of plastic packaging waste, the incorporation of enhanced recyclability into product design, and the adoption of innovative recycling or recycling-enabling technologies.

[0005] One significant factor that hinders the recyclability of plastic packaging is the use of printing inks. Printed on packaging for essential consumer information and branding, these inks can become contaminants if not removed before recycling. Such impurities can lead to lower quality recyclates. Therefore, implementing a de-inking process that separates the ink from the substrate prior to recycling could be a valuable solution to eliminate this impurity and facilitate a more efficient recycling process.

[0006] W02023 / 007370 A1 discloses a clear primer coating for recyclable PET-g shrink-sleeve labels, which is curable upon exposure to UV light. The primer composition comprises one or more monofunctional or difunctional radiation-curable monomers and a photoinitiator, resulting in an acid value of 50 - 135 mg KOH / g. Additionally, the primer composition includes a cellulosic polymer, an acid-functional radiation-curable monomer, and a multifunctional radiation-curable monomer with an acrylate functionality of at least 3. The cellulosic polymer consists of one or more cellulose derivatives, preferably ester and / or ether derivatives. Cellulose derivatives are often more expensive due to the additional processing required. Further, depending on the modification process, there may be environmental concerns related to the production of cellulose derivatives.

[0007] KR 2024 0064429 A discloses a 3D printing ink composition for manufacturing artificial-organ

[0008] A24219WO / 16 . 02 . 2026 / hydrogels based on an interpenetrating network of agarose and polyacrylamide, together with specific crosslinkers and photoinitiators, to mimic the mechanical properties of human tissues. The composition is an aqueous system containing agarose as a physically gelling polysaccharide and acrylamide as a polymerizable monomer that forms polyacrylamide under UV initiation. Chemical crosslinking is achieved via N,N-methylenebisacrylamide and / or polyethylene glycol diacrylate, while UV-sensitive photoinitiators control curing speed and network formation.

[0009] JP2022080724 describes a print ink composition for detachment comprising a pigment, a binder resin, and a rosin-based resin with an acid value of 100-350 mg KOH / g, present at 0.1-5.0 mass% in the ink composition, along with an organic solvent.

[0010] EP4435062 discloses a primer composition for delaminating and / or deinking a substrate. This solventbased primer composition includes, as a first binder component, a modified rosin resin selected from maleic-modified or fumarate-modified rosin resins with an acid value in the range of 50 to 300 mg KOH / g, which are dispersible in an alkaline medium, as well as a film-forming polyurethane.

[0011] JP3776264 describes an ink composition containing a cellulosic resin, or a mixture of the cellulosic resin with an acrylic resin, an acrylpolyol resin, or a urethane resin, together with one or more resins selected from styrene-acrylate resins, styrene-maleate resins, and rosin-maleate resins, as main vehicle components. The releasable ink composition can be removed from a printed substrate by printing the substrate with the composition and subsequently contacting the printed substrate with an alkaline aqueous solution.

[0012] WO2023 / 150251 provides a method for recycling plastic articles, such as bottles and labels affixed to bottles, that are printed with UV-curable inks. The inks and colorants are removed as solid particles upon treatment with a hot alkaline solution, yielding colorless or nearly colorless plastic materials suitable for recycling without contamination from inks or colorants.

[0013] WO2021081288 discloses an ink composition comprising a resin, a solvent, and a colorant resistant to dissolution in a hot caustic solution. This ink composition is designed to withstand dissolution during plastic material recycling processes that utilize a hot caustic wash, particularly for crystallizable PET-G substrates on which the ink composition has been printed and subsequently removed, ensuring that the plastic material remains free from staining or contamination by the ink.

[0014] A24219WO / 16 . 02 . 2026EP 3611232 A1 discloses a printing ink or coating composition that optionally contains colorants and one or more derivatives of starches or modified starches.

[0015] EP 2703180 A1 describes a free radical radiation-curable liquid that includes a photoinitiator, and a monomer or oligomer containing an alkali hydrolyzable group. The alkali hydrolyzable group is an oxalate group, located within the atomic chain between two free radical polymerizable groups of the monomer or oligomer.

[0016] WO2024 / 105376 A1 relates to a printing ink composition that comprises one or more keratin-based pigments and water, wherein the average particle size of the keratin-based pigments does not exceed 3000 nm.

[0017] WO 2021 / 165081 A1 discloses a deinking primer composition designed for the deinking of a substrate. This deinking primer composition contains a binder component with a polymeric backbone featuring pendent hydroxy or carboxy groups that have been esterified, acetalized, or ketalized. Consequently, a primer layer prepared from this deinking primer composition is dissolvable in an alkaline aqueous medium.

[0018] Polysaccharides are typically not utilized in UV-curable coatings due to their potential to adversely affect various properties such as viscosity, chemical stability, flow, self-leveling, water resistance, and susceptibility to mildew. Consequently, when polysaccharides are incorporated in the prior art, they are in a modified form. This modification often involves the esterification or oxidation of glycosidic bonds or the creation of copolymers with other components. A common example of this is cellulose acetate. However, coatings formulated with modified cellulosic polymers tend to exhibit very poor deinking properties in NaOH solutions, as noted by S. Ugdiiler et al. in the Journal of Hazardous Materials, 452 (2023) 131239.

[0019] Furthermore, there are numerous examples of deinking units implemented by major converters and recyclers, primarily aimed at treating post-industrial waste due to limitations in sorting technologies for post-consumer waste. However, the variability in ink composition and substrate types, along with the requirement for inks to adhere firmly to substrates without delaminating during use, complicates the

[0020] A24219WO / 16 . 02 . 2026deinking process. This challenge is particularly pronounced when dealing with radiation-cured inks and / or overprint varnishes, which make the deinking even more difficult. Additionally, continuous efforts are underway to enhance the speed and efficiency of the deinking process, enabling seamless integration into the recycling workflow while keeping costs and process footprint minimal.

[0021] In conclusion there is still a need to develop new raw materials that can be used in primers or inks formulations to help the de-inking without compromising adhesion during use, transportation and distribution or other important properties like optical features or flexibility.

[0022] The objective of the present invention is, therefore, to provide radiation-curable compositions that enable de-inking on a wide range of substrates.

[0023] The problem is solved by the composition according to claim 1. Further preferred embodiments are subject of the dependent claims 2 to 15.

[0024] The present invention relates to a primer composition comprising one or more of a monofunctional or multifunctional radiation curable monomer having a molecular weight of less than 1000 Dalton or a mixture thereof, a photo initiator, an inert resin, and an oligomer having a molecular weight of 1000 Dalton or more, characterized in that the composition additionally comprises at least one chemically unmodified polysaccharide, whereby the polysaccharide may be hydrolyzed to adjust its chain length, but has not been chemically modified through esterification, etherification, oxidation, or substitution of its functional groups and wherein reductions in chain length are achieved by hydrolysis of glycosidic linkages to reduce chain length without introducing substituents or altering the repeating sugar units. Surprisingly, the composition according to the present invention demonstrates outstanding adhesion, overprintability, flexibility, and water resistance. In addition, it was found that the composition, which includes these polysaccharides, exhibits good viscosity, excellent chemical stability, enhanced flow characteristics, effective self-leveling ability, improved water resistance, and reduced susceptibility to mold. Notably, it can be used in the broadest number of ink types and is efficient and compatible with the commonly used treatments that plastics undergo before and / or during recycling, such as washing. Complete deinking can be obtained by a caustic water wash treatment, even though it contains unmodified polysaccharides. This finding showcases the unique performance capabilities of the composition, challenging the common assumptions regarding the limitations traditionally associated

[0025] A24219WO / 16 . 02 . 2026with unmodified polysaccharides. The use of unmodified polysaccharides not only provides excellent deinking characteristics but is also cost-effective and sustainable. Their simplicity in production, alignment with natural product trends, and established safety profiles make them attractive for those looking to minimize costs.

[0026] Within the context of the present invention, the term “chemically unmodified polysaccharide, whereby the polysaccharide may be hydrolyzed to adjust its chain length, but has not been chemically modified through esterification, etherification, oxidation, or substitution of its functional groups and wherein reductions in chain length are achieved by hydrolysis of glycosidic linkages to reduce chain length without introducing substituents or altering the repeating sugar units” refers to a polysaccharide that retains its original chemical composition and structure of monomer units as naturally occurring, except for potential reductions in molecular weight or chain length achieved through hydrolysis. Such hydrolytic treatment does not alter the fundamental chemical integrity of the polysaccharide, as the functional groups and glycosidic bonds remain chemically unaltered beyond the cleavage of bonds necessary for chain length adjustment. Thus, it refers to a polysaccharide that, apart from a possible reduction in polymer chain length by hydrolytic chain scission, remains in its natural, unmodified chemical state. Hydrolysis cleaves glycosidic linkages to adjust the chain length. Each cleavage event converts one polymer chain into two shorter chains and therefore increases the number of chain ends. Specifically, new terminal monosaccharide residues are created at the cleavage site: one end becomes a reducing end (bearing a free anomeric hemiacetal or hemiketal capable of ring opening), and the opposite end becomes a non-reducing end (with the anomeric center remaining blocked in a glycosidic linkage). Apart from this end-group formation and the resulting change in chain-length distribution, hydrolysis does not introduce new substituents or alter the chemical identity of the repeating sugar units. In particular, the process does not involve chemical derivatization such as esterification, etherification, oxidation, or substitution. Examples include the partial hydrolysis of cellulose to produce microcrystalline cellulose, which occurs without involving chemical derivatization or modification of functional groups. Preferably, such a hydrolyzed polysaccharide has an average molecular weight of more than 100’000 Dalton, more preferably more than 150’000 Dalton.

[0027] Within the context of the present invention, the term “molecular weight” refers to the number-average molecular weight (Mn). For substances for which the molecular weight is not unambiguously derivable

[0028] A24219WO / 16 . 02 . 2026from the chemical structure, Mn is determined by GPC using polystyrene calibration in accordance with ISO 11344:2016.

[0029] In a preferred embodiment, the chemically unmodified polysaccharide is in its original natural form, meaning it has also not undergone any hydrolysis reaction. This approach avoids an additional reaction step, thereby reducing costs.

[0030] The composition according to the present invention comprises one or more of a monofunctional, or multifunctional radiation-curable monomer or a mixture thereof. The term multifunctional stands more than one group that can be cured. This encompasses for example difunctional, trifunctional and / or tetrafunctional. The term "mixture" can encompass, for example, two different monofunctional radiation-curable monomers, a combination of a monofunctional and a difunctional radiation-curable monomer, a combination of a difunctional and a trifunctional radiation-curable monomer, a mixture that includes three different types - monofunctional, difunctional, and trifunctional radiation-curable monomers together or even a mixture that includes four different types - monofunctional, difunctional, trifunctional and tetrafunctional. These monomers undergo polymerization upon exposure to radiation such as ultraviolet (UV) light or an electron beam. In a preferred embodiment, the composition comprises a mixture of radiation-curable monomers, wherein at least 30%, and preferably 50%, of the radiation-curable monomers are multifunctional radiation-curable monomers. Examples of the composition include a mixture comprising difunctional, trifunctional, and tetrafunctional monomers in a ratio of 1:1 :0.5, with no monofunctional monomers present (meaning that 100% of the mixture consists of multifunctional monomers). Such monomer mixtures have demonstrated good results.The composition further includes a photoinitiator, which is essential for initiating the polymerization process. This compound absorbs the radiation energy and generates reactive species, such as free radicals or cations, that trigger the polymerization of the monomers and oligomers within the system. The incorporation of a photoinitiator ensures rapid curing under controlled conditions, enabling the formation of a robust and uniform primer layer.

[0031] An inert resin is also present in the composition, providing essential properties such as adhesion, flexibility, and mechanical strength. This resin does not participate in the curing reaction but acts as a binder, ensuring proper cohesion of the cured film with the substrate and subsequent layers. The inert resin also helps to stabilize the overall formulation and improve its compatibility with diverse surfaces.

[0032] A24219WO / 16 . 02 . 2026Examples are polyvinyl butyral (PVB), acrylic resins, polyurethane resins, epoxy resins, aldehyde resins and phenolic resins.

[0033] Furthermore, the composition comprises an oligomer having a molecular weight of 1000 Dalton or more that contributes to the structural and functional properties of the cured primer. These oligomers generally have molecular weights ranging from 1000 to 5,000 Daltons. They enhance the viscosity, mechanical strength, and thermal or chemical resistance of the primer. Together, these components synergistically ensure the primer achieves optimal adhesion, durability, and compatibility with the intended application environment. Typical oligomers are, for example, epoxy acrylates, polyester acrylates, polyether acrylates, urethane acrylates, silicone acrylates, and vinyl ether oligomers.ln addition, the composition can comprise a monofunctional acrylated amine synergist present to mitigate oxygen inhibition. The monofunctional acrylated amine is a compound that features one acrylate group along with an amine functional group. This particular structure allows the compound to participate actively in the polymerization reaction. The presence of the monofunctional acrylated amine synergist can enhance the curing process.

[0034] Preferably, the polysaccharide contained in the composition according to the present invention is selected from the group consisting of cellulose, agarose, agar, glycogen, inulin, heparin, hyaluronic acid, chitin, xylan, arabinoxylan, mannan, galactomannan, pectin and starch or a mixture thereof. All these polysaccharides facilitate deinking.

[0035] More preferably, the polysaccharide is selected from the group consisting of agarose, agar, glycogen, inulin, heparin, hyaluronic acid, chitin, xylan, arabinoxylan, mannan, galactomannan, pectin and starch or a mixture thereof as they have good water-solubility.

[0036] Even more preferably, the polysaccharide is selected from the group consisting of agarose, agar, glycogen, inulin, and starch, and even more preferably agarose, and starch. These compounds are primarily composed of monosaccharides linked by glycosidic bonds and do not contain additional functional groups such as carboxyl, amino, or sulfate groups. All said polysaccharides have an acid value of essentially 0, meaning they possess no significant amount of free titratable carboxylic acid groups under normal conditions. This indicates that the polysaccharides are predominantly neutral in their chemical structure and lack the acidic functional groups that could contribute to the acid value.

[0037] A24219WO / 16 . 02 . 2026that can be hydrolyzed when reacting during caustic deinking process. These polysaccharides, particularly agarose and starch, contain numerous hydroxyl (-0H) groups. The presence of these hydroxyl groups allows for hydrogen bonding, which enhances the polysaccharides' interactions with hot water during the deinking process.

[0038] Good results can be achieved with starch due to its excellent swelling properties. Examples are starches selected from the group consisting of waxy corn starch, sticky rice starch (extracted from glutinous rice (Oryza sativa)), tapioca starch, potato starch, wheat starch, regular corn starch, mediumgrain rice starch and long-grain rice starch. Particularly preferred are starches with an amylopectin content of 75% or more by weight, based on the dry weight of the starch. Amylopectin, as a highly branched glucose polymer, promotes the formation of larger starch granules. These larger granules provide more space for water uptake and facilitate the swelling process. Additionally, such a high amylopectin content leads to a looser internal structure within the starch granules. This structure is less densely packed compared to starches with higher amylose content, resulting in amorphous regions that are more accessible to water. This loose granular structure also creates a porous surface, further enhancing water penetration into the starch granules. Together, these properties result in superior water absorption and improved swelling capacity. Especially preferred are waxy corn starch, sticky rice starch, tapioca starch, potato starch, and most preferably potato starch.

[0039] Preferably, the composition according to the present invention has an acid value of less than 20 mg KOH / g, preferably less than 15 mg KOH / g. The acid value is measured by taking a known weight of the sample, dissolving it in a suitable solvent, and titrating it with a standard potassium hydroxide (KOH) solution. An acid value of less than 20 mg KOH / g, preferably less than 15 mg KOH / g allows for good deinking while maintaining high print quality. Additionally, it leads to less residue formation, yielding cleaner recycling.

[0040] The composition according to the present invention may have a polysaccharide content between 5 and 20% by weight, preferably 8 to 12 % by weight, and ideally about 10% by weight based on the total composition. Such a polysaccharide content results in an excellent ink removal from a variety of different substrates.

[0041] A24219WO / 16 . 02 . 2026The monofunctional or multifunctional radiation curable monomer of the composition according to the present invention having a molecular weight of less than 1000 Dalton can comprise an acrylate or a methacrylate group. These functional groups are highly reactive and enable rapid and efficient polymerization under radiation curing, such as UV or electron beam exposure. This results in the quick hardening of the primer layer, which brings significant advantages in production. Monofunctional monomers can create more flexible and elastic coatings, while multifunctional monomers form tougher and more chemically resistant networks. Further, including a trifunctional monomer boosts the reactivity of the coating and enhances chemical resistance. Moreover, the radiation-durable nature of these monomers ensures that the cured material withstands UV exposure and environmental degradation, contributing to the longevity and durability of the print. Additionally, the chemical structure of acrylates and methacrylates enhances adhesion between different layers in the ink formulation, such as between the primer composition and the ink or between the primer composition and challenging substrates like plastics, metals, or glass. This adhesion is beneficial for achieving high-quality, long-lasting prints.

[0042] The present invention also relates to a printed product comprising a substrate and at least one primer layer applied to at least one surface of said substrate, wherein said at least one primer layer is made from a deinking primer composition according to the present invention. The substrate serves as the foundational material of the printed product, and it is made from recyclable materials such as plastic or metal. By using these types of substrates, the invention aims to promote sustainability and environmental responsibility in the printing industry. The composition according to the present invention not only improves the adherence of inks, ensuring optimal performance of the printed product, but also facilitates the subsequent recycling process. The composition enhances the surface characteristics of the substrate, allowing for easier detachment of inks when the printed product is subjected to deinking processes. Consequently, this innovation plays a dual role as it supports the effective functioning of printed products while significantly contributing to their environmental sustainability.

[0043] The printed product may further comprise a printing ink layer on the side of the primer layer that is not in contact with the substrate. Within the context of the present invention, “not in contact with the substrate” means that there is a complete separation between the printing ink layer and the substrate,

[0044] A24219WO / 16 . 02 . 2026i.e., the ink layer is completely on the primer layer. This arrangement is beneficial for ensuring high-quality printing outcomes and facilitating the deinking process. Moreover, this configuration is preferred for the deinking process. By having the primer layer act as a barrier between the substrate and the ink, it creates a separation that allows for more effective ink removal during recycling operations. Water can penetrate the primer layer, facilitating contact with the polysaccharide, particularly with the functional groups within it. The complete separation of the ink layer from the substrate by the composition according to the present invention enhances the ability to detach the ink layer completely from the substrate.

[0045] Preferably the substrate of the printed product is a plastic material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, acrylonitrile-butadiene-styrene, polymethyl methacrylate, and polyamide. The composition of the present invention enables the effective removal of ink, enhancing the purity and quality of recycled plastic. By eliminating residual inks that could potentially discolor the material, the mechanical properties are preserved, ensuring its suitability for high-value applications. These plastics are widely used in consumer products and packaging, where printing is often applied for branding, labeling, and product information.

[0046] Preferably, the printed products are selected from the group consisting of flexible packaging, labels, and shrink sleeves. The composition according to the present invention also enables the effective deinking of such challenging products. Despite their very thin substrates, often having a substrate thickness of less than 200 pm, they can be successfully deinked, which was often ineffective with methods known in the prior art.

[0047] A further aspect of the present invention relates to the process of making printed products and of deinking the same.

[0048] The process for making printed products comprises the step of applying a primer composition onto a substrate. The primer composition can be applied, for example, through roll coating, spraying, screen printing, screen and flexographic printing, gravure, or offset printing. The applied coating thickness can range from 2 to 15 microns, depending on the application and printing method, with a preferred

[0049] A24219WO / 16 . 02 . 2026thickness of between 6 and 12 microns. Subsequently, the primer composition is dried or cured, with curing being conducted using for example UV light, by LED or electron beam-curing.

[0050] The process deinking printed products comprises the step of treating the printed product in an alkaline aqueous medium so as to detach the primer layer that is present on the printed product. This can be done for example by immersing the printed product in an alkaline aqueous solution or by applying the solution through spraying or soaking. For fast deinking, immersion is preferred due to the beneficial mechanical effect of friction. The alkaline medium effectively detaches the primer layer, allowing for the removal of inks. Following this treatment, the printed product can be rinsed to eliminate remaining residues, ensuring a clean substrate for subsequent recycling or repurposing.

[0051] Preferably, the temperature during the deinking process is between 50°C and 90°C, most preferably 60°C to 85°C. When polysaccharides are subjected to an alkaline aqueous medium at elevated temperatures, various chemical and physical changes can occur, resulting in a decrease in adhesion of the primer composition.

[0052] Preferably, said step of treating the printed product is conducted for a time in the range between 1 to 20 min, preferably 1 to 10 min, most preferably 2 to 6 min. Within this time frame a complete deinking can be achieved.

[0053] The alkaline aqueous medium can additionally comprise a surfactant, which reduces surface tension, helps detach ink, and aids in its removal through flotation.

[0054] The composition according to the present invention can be used as a protective coating, for example, for direct-to-plastic printing, as well as an overprint varnish, particularly for printed paper and cardboard. Due to its excellent deinking properties, it enables efficient recycling by allowing inks to be easily removed.

[0055] Figure 1 shows PET flakes previously coated with primer formulations according to the prior art (FIF , example 1) and a standard blue UV curable ink, showing incomplete deinked surface after 10 min caustic water treatment.

[0056] Figure 2 shows PET flakes previously coated with primer formulations according to the prior art (F5-F7, example 2) and a standard blue UV curable ink, showing incomplete deinked surface after 10 min

[0057] A24219WO / 16 . 02 . 2026caustic water treatment.

[0058] Figure 3 shows a PET substrate previously coated with a composition according to the present invention (Primer F7) and a standard blue UV curable ink, showing complete deinked surface after 10 min caustic water treatment.

[0059] Example 1

[0060] Primer formulations

[0061] F1-F4 were prepared using an alkali soluble coresin (Neocryl B817) and varying the ingredients ratio to adjust deinkability, solvent resistance and surface hardness of the primer.

[0062] A standard blue UV curable ink was applied on top of each primer formulation. As shown in Table 2 after 30 min deinking treatment, the substrate surface still was covered for more than 50% of ink.

[0063] Table 1: Primer formulations

[0064]

[0065] A24219WO / 16 . 02 . 2026

[0066]

[0067] Table 2: Properties of the formulations after curing (Fusion lamp H bulb 240 W / cm) and deinking

[0068]

[0069] Example 2

[0070] New formulations F5-F7 were prepared introducing highly ethoxylated monomers to increase the solubility of the primer. However also in this case the deinking treatment was not affective after 30 min, as shown in Table 4.

[0071] Table 3: Primer formulations

[0072]

[0073] A24219WO / 16 . 02 . 2026

[0074]

[0075] Table 4: Properties of the cured (Fusion lamp H bulb 240 W / cm) formulations

[0076]

[0077] Example 3

[0078] Formulation F8 was prepared introducing 10% of Agarose as deinking additive and as it shown in Table 4.

[0079] Table 4: Primer formulation containing a saccharide as deinking additive

[0080]

[0081] A24219WO / 16 . 02 . 2026

[0082]

[0083] Unlike the comparative examples, the composition of the present invention enables the substrate to be deinked using the same method in just 10 minutes. The results are shown in Figure 3. The results highlight that the use of unmodified polysaccharides maintains essential properties of the primer composition, such as adhesion, overprint ability, flexibility, and water resistance, while ensuring complete deinking after caustic water wash treatment.

[0084] A24219WO / 16 . 02 . 2026

Claims

Claims1. A primer composition comprising one or more of a monofunctional, or multifunctional radiation curable monomer having a molecular weight of less than 1000 Dalton or a mixture thereof, a photo initiator, an inert resin, and an oligomer having a molecular weight of 1000 Dalton or more, characterized in thatthe composition additionally comprises at least one chemically unmodified polysaccharide, whereby the polysaccharide may be hydrolyzed to adjust its chain length, but has not been chemically modified through esterification, etherification, oxidation, or substitution of its functional groups, and wherein reductions in chain length are achieved by hydrolysis of glycosidic linkages to reduce chain length without introducing substituents or altering the repeating sugar units.

2. Composition according to claim 1, wherein the polysaccharide is selected from the group consisting of cellulose, agarose, agar, glycogen, inulin, heparin, hyaluronic acid, chitin, xylan, arabinoxylan, mannan, galactomannan, pectin and starch or a mixture thereof.

3. Composition according to claim 1, wherein the polysaccharide is selected from the group consisting of agarose, agar, glycogen, inulin, heparin, hyaluronic acid, chitin, xylan, arabinoxylan, mannan, galactomannan, pectin and starch or a mixture thereof.

4. Composition according to any of the preceding claims, wherein the polysaccharide is selected from the group consisting of agarose, agar, glycogen, inulin, and starch, preferably starch and agarose, most preferably starch.

5. Composition according to any of the preceding claims, wherein the starch is selected from the group consisting of waxy corn starch, sticky rice starch, tapioca starch, potato starch, wheat starch, regular corn starch, medium-grain rice starch and long-grain rice starch, preferably waxy corn starch, sticky rice starch, tapioca starch and potato starch, most preferably potato starch.

6. Composition according to any of the preceding claims, wherein the polysaccharide content is between 5 and 20% by weight, preferably 8 to 12% by weight, and ideally about 10% by weightA24219WO / 16 . 02 . 2026based on the total composition.

7. Composition according to any of the preceding claims, wherein the monofunctional or multifunctional radiation curable monomer comprises an acrylate or a methacrylate group.

8. Printed product comprising a substrate and at least one primer layer applied to at least one surface of said substrate, wherein said at least one primer layer is made from a deinking primer composition according to any of claims 1 to 7.

9. Printed product according to claim 8, further comprising a printing ink layer on a side of said primer layer that is not in contact with said substrate.

10. Printed product according to claim 9, wherein the substrate is a plastic material selected from the group consisting of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, acrylonitrile-butadiene-styrene, polymethyl methacrylate, and polyamide.

11. Printed product according to any of claim 8 to 10, wherein said printed product is selected from the group consisting of a flexible packing, a label and a shrink sleeve.

12. Method of making a printed product according to any of claims 8 to 10, comprising the step of applying a primer composition according to any of claims 1 to 6 onto a substrate.

13. Method of deinking a printed product according to any of claims 8 to 10, comprising a step of treating the printed product in an alkaline aqueous medium so as to detach the primer layer that is present on the printed product, preferably at a temperature between 50°C and 90°C, most preferably 60°C to 85°C.

14. Method according to any of claims 13 to 14, wherein said step of treating the printed product is conducted for a time in the range between 1 to 20 min, preferably 1 to 10 min, most preferably 2 to 6 min.

15. Method according to any of claims 13 to 15, wherein the alkaline aqueous medium additionally comprises a surfactant.A24219WO / 16 . 02 . 2026direct-to-plastic printing and as an overprint varnish.A24219WO / 16 . 02 . 2026

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