Print Quality of Coated Paper from Invasive Alien Plant Goldenrod

Abstract

When designing products with a shorter lifespan, such as packaging and graphic products, sustainability and circular economy are particularly important. The use of an alternative fiber source for papermaking, such as collected biomass from invasive alien plant species (IAPS), is a good example of sustainable natural resource management, where IAPS are seen as a potential source of various new products. The aim of the present study was to analyze the printability of paper made from the IAPS Goldenrod. CMYK prints were made using inkjet digital technology, and their print quality was determined. IAPS Goldenrod paper, with its natural brownish color, low gloss, high voluminosity, high surface roughness and porosity, shows inferior print quality compared to recycled office paper. In order to improve the printability of this paper, surface coating using three different wet film depositions was applied. The results indicate that the smallest coat weight used suppresses the color and inferior properties of IAPS Goldenrod paper efficiently, resulting in similar printability for both the analyzed papers. Only a small difference in print quality between coated IAPS Goldenrod and recycled paper was determined, suggesting that low-value, non-demanding graphic products and packaging could be made from the coated IAPS Goldenrod paper.

1. Introduction

Sustainability and the circular economy are important strategic development directions in most European countries. In Slovenia, the development strategy for 2030, a low-carbon circular economy, promoting innovation and developing products that use raw materials and energy more efficiently, and sustainable natural resource management are important goals that must also be implemented in the design of printed products [1]. When designing products with a shorter lifespan, such as most printed products, the efficient use of materials, the use of materials from renewable sources, and a design for recycling and reuse are particularly important [2,3].

The APPLAUSE project (Alien Plant Species from Harmful to Useful with Citizens’-led Activities) addressed the possibility of using invasive alien plants as raw materials for various products as part of the circular economy [4]. Currently, invasive alien plants in Slovenia are composted or, as part of collected biomass, taken to incineration. Ljubljana, as a “zero waste city”, has recognized the potential of collected biomass for the development of new sustainable products.

In the city of Ljubljana, 150 alien plant species were identified; among them, many were also invasive [4]. Invasive alien plant species (IAPS) are non-native plants that have been transported from outside their natural ecological range to new habitats. IAPS are one of the greatest challenges in European ecosystems because they displace native vegetation and destroy agricultural land and their spread disturbs the balance of natural ecosystems and habitat biodiversity [5].

Besides wood, a large number of plants represent potential sources of fibers for papermaking: straws, grasses, reeds, various stem, leaf and seed fibers from annual, and perennial plants [6]. Among the annual plants, cereal straws and the fibrous residues of sugar cane are used the most. Several studies show that invasive plant species can be a more or less rich source of cellulose fibers, too. Cabrera-García et al. investigated the use of Pennisetum setaceum in their application as a reinforcement of polymeric materials for injection molding [7]. Agave americana L. has shown great potential to be used as a reinforcement in polymer composites [8]. Razzak et al. reported that Schinus molle is an interesting alternative source for producing cellulose fibers that can be utilized in the textile and papermaking industries, as well as in cellulose fiber-based composites [9].

The invasive plants Spartina alterniflora, Eichhornia crassipes, and Ailanthus altissima were investigated as an alternative raw material for pulp and paper [10,11,12]. Recently, in a study by Kapun et al., seven fast-growing invasive plant species were tested for their valorization potential in the pulp and paper industry [13].

Zihare and Blumberga looked at the possibility of products from combined resources, such as woody crops, forest residues, and invasive species, entering existing cellulose product markets [14], while the importance of lignocellulose from wood and IAPS plants has been investigated by Saldarriaga-Hernández et al. [15], Sánchez and Montoya [16], and LIU et al. [17]. Research by Gregor Svetec et al. showed that paper and cardboard could be used for the design of a unique graphic product [18]. The research by Lavrič et al. [19] and Karlovits et al. [20] showed that the Japanese knotweed could be used as a raw material in the paper industry, but in order to achieve good printability, its paper properties need to be improved. This improvement can be achieved through surface coating, which has been widely used in the paper industry over the past several decades [21]. For obtaining the final paper/cardboard and print quality, coating layer thickness, surface and bulk porosity, surface roughness, and pigment particle, namely bio-based coating details, are important parameters to follow [22,23,24,25,26,27].

The aim of the present study was to analyze the print quality of coated paper made from IAPS. The Solidago gigantea (Giant Goldenrod), as one of the most used IAPS in Europe, was used for paper production. This plant was chosen because, in the past, the main focus when dealing with IAPS was namely the Japanese Knotweed (Fallopia japonica), and we wanted to stress the importance of other IAPS as well. Giant Goldenrod is a herbaceous perennial, up to 2.8 m tall [5]. The stems are unbranched, except in the inflorescence, and the leaves are simple and alternate, stalkless, and three-nerved. It is an ornamental plant that groves in forest glades and edges, railroad and road sides, riverbanks, urban and peri-urban areas, agricultural areas, plantations and orchards, forests, and meadows [28]. The surface properties of uncoated and coated paper and the print quality of inkjet prints on IAPS Goldenrod paper were measured and compared to prints on recycled office paper.

2. Materials and Methods

2.1. Materials

The medium-grammage paper (100 g/m²) was made from a mixture of 55% wood fibers and 45% invasive plant fibers, in the ratio 45% fibers of the Giant Goldenrod, 25% spruce, and 30% eucalyptus fibers. This ratio was determined based on the preliminary research, with the goal to use as much IAPS as possible to obtain paper with suitable properties. The chemical analysis showed that the Giant Goldenrod is composed of 37% of cellulose, 36% of hemicellulose, 19% of lignin, 2.3% of ash, 1.6% ethanol, and 0.6% hexane extractives [5]. Compared to wood fibers, the cellulose content as well as the lignin content are lower, whereas the content of hemicellulose is higher.

The fibers were obtained from different sources. The fibers of the Giant Goldenrod were obtained through urban harvesting from the air-dried biomass plant stems (without leaves, flowers, and roots). They were delignified in an alkaline process. Chipped stems were cooked for 3 h in a 2% solution of sodium hydroxide. The pH of the cooking solution was 12.6, and the temperature was 75 °C. In the next step, the pulp was processed in a Valley beater for 15 min to obtain the appropriate papermaking properties. The drainability of the prepared IAPS pulp suspension was 33 °SR, while the °SR value for suspension produced from wood fibers is usually 10–15 °SR, or it can be up to 70 °SR if the nanocellulose fibers are added to the suspension. The following pulp properties were obtained: tensile index = 26.4 Nm/g, tearing index = 1.5 mNm²/g, and bursting index = 0.89 kPam²/g.

For the production of paper, the wood fibers in the form of commercial bleached sulphate cellulose pulp were added, together with the filers CaCO₃ (8.5%), retention agent (0.03%), cationic starch (0.75%), and paper size agent AKD (2.5%), which were added to reduce the fiber absorbency of water. The paper was produced on a pilot paper machine (Andritz AG, Graz, Austria) located in the Pulp and Paper Institute, Ljubljana, Slovenia. Paper is further on marked as Goldenrod.

The commercial office paper (Lettura, Heinsberg Papier, Freital, Germany) with declared grammage of 80 g/m², marked as Recycled, was manufactured from 100% recycled fibers, and was used for comparison.

2.2. Coating and Printing

For coating, a commercial coating solution with a viscosity of 1000 mPa.s and 68% dry matter, containing clay and calcium carbonate, was obtained from a paper mill. The consumption of coating solution was around 2 mL per sheet. Both papers (Goldenrod and Recycled) were coated using a wire-wound bar only on the upper (A) side of a paper using the lab RK Multi Coater K303S. The coat weight was varied by varying the diameter of the wire on the bar. Three bars were used: No. 1 with a wire diameter of 0.08 mm, No. 5 with a wire diameter of 0.64 mm, and No. 8 with a wire diameter of 1.27 mm. After coating, the samples were allowed to dry overnight at room temperature.

The full-tone color prints were produced on the Epson WorkForce Pro WF-C579R inkjet printer.

In

Table 1. Sample identification and description.

Sample Identification	Sample Description
GP	Paper from IAPS Goldenrod; uncoated
GP-1	Paper from IAPS Goldenrod; coated; bar No. 1
GP-5	Paper from IAPS Goldenrod; coated; bar No. 5
GP-8	Paper from IAPS Goldenrod; coated; bar No. 8
RP	Recycled paper; uncoated
RP-1	Recycled paper; coated; bar No. 1
RP-5	Recycled paper; coated; bar No. 5
RP-8	Recycled paper; coated; bar No. 8

, the identification and description of the analyzed samples are summarized.

2.3. Methods

Paper samples were conditioned in a standard atmosphere, according to standard ISO 187, at a temperature of 23 °C and relative humidity of 50%. The basic paper properties, grammage (ISO 536), thickness, and density (ISO 534), were determined according to standardized methods. The mass was determined with an analytical balance Mettler Type AE200 (Columbus, OH, USA) with a readability of 0.1 mg. Coating weight was obtained by subtracting from the weight of a defined area of coated paper the weight of the same-sized area of uncoated paper. The thickness of samples was measured in accordance with ISO 534, using a micrometer from Mitutoyo (Kawasaki, Japan) with 0.001 mm accuracy.

The surface properties were tested according to their respective standards. The surface roughness and air permeability were determined on the felt side of paper using a Bendtsen N3500 roughness and air permeability tester (PTA Group, Spain, France) (ISO 8791-2, ISO 5636-2). The specular gloss was measured using a gloss meter, Zehntner Gloss 1022 (Zehntner GmbH Testing Instruments, Sissach, Switzerland) (ISO 8254-1). The yellowness of the papers (DIN 6167), the ISO brightness of the coated papers (ISO2470), and the CIELAB color coordinates of the prints (ISO 5631-1) were determined with a spectrophotometer X-Rite i1 Pro 2b (X-Rite, Grand Rapids, MI, USA). On average, 10 replicates were performed per sample per test. The results of these 10 measurements were then averaged. The sample standard deviation (SD) was calculated using the following equation:

$$s^2=\frac{1}{N-1}\sum _{i=1}^N{\left(x_i-\overline{x}\right)}^2$$

The colorimetric measurements and computations were performed in line with the ISO 13655 standard using a spectrophotometer with (45°a:0°) measurement geometry and white backing, D65 illuminant, and a 10° standard observer. Delta E_ab* (or ∆E_ab*), which is a calculation of the change in color, as measured in the Hunter Lab color space on a three-dimensional axes, L* a* b*, was determined using following equation:

$$∆E_{ab}^{*}=\sqrt{{(∆L^{*})}^2+{(∆a^{*})}^2+{(∆b^{*})}^2}.$$

The optical density (OD) of the prints, which is a measure of the light absorbance of a material, was measured using a Gretag Matcbeth D19C densitometer (X-Rite, Grand Rapids, MI, USA).

The surface and cross-section of the coated papers were examined with scanning electron microscopy (JSM-6060 LV, Jeol, Tokyo, Japan). A stereo microscope, Leica S9i, (Leica Microsystems, Wetzlar, Germany) was used to take a picture of the paper surface and prints. The typographic tonal density (TTD) of the prints was determined via an image analysis. The ImageJ program was used to determine the increase in the halftone value of the black element on a white and yellow background and the yellow element on a black background.

3. Results and Discussion

3.1. Paper Characteristics

A single-layer method was used to apply the coating solution onto the base paper. Three bars with different wire diameters were used, No. 1, No. 5, and No. 8, for depositing 6, 50, and 100 μm of wet film onto the paper substrate, which resulted in different coat weights, ranging from 27 g/m² to 131 g/m², depending on bar used and the type of paper.

The coat weight is in high correlation with the grammage, thickness, and paper density, as expected, though the difference between the papers is also evident. Paper from IAPS has a lower density (557 kg/m³) than standard paper made from wood fibers (712 kg/m³), which is also seen in our case (

Table 2. Basic and surface properties of samples given as mean value and standard deviation.

Sample	Grammage (g/m2)	Thickness (µm)	Density (kg/m3)	Roughness (mL/min)	Air Permeability (mL/min)	Specular Gloss (%)	ISO Brightness (%)
GP	104.7 ± 1.1	188 ± 4	557 ± 13	1502 ± 151	1418 ± 68	3.6 ± 0.3	/
GP-1	131.8 ± 1.8	198 ± 2	665 ± 14	1460 ± 207	229 ± 27	22.1 ± 4.0	67.0 ± 2.2
GP-5	161.3 ± 5.1	228 ± 6	708 ± 31	1360 ± 240	368 ± 71	38.4 ± 3.6	83.7 ± 1.9
GP-8	207.6 ± 2.7	260 ± 4	799 ± 16	1240 ± 277	256 ± 21	39.2 ± 1.1	86.3 ± 0.7
RP	77.6 ± 1.1	109 ± 2	712 ± 15	238 ± 28	64 ± 3	5.0 ± 0.2	60.0 ± 3.0
RP-1	120.5 ± 1.6	145 ± 11	857 ± 15	1020 ± 239	19 ± 5	45.5 ± 1.4	81.8 ± 2.7
RP-5	167.6 ± 12.3	158 ± 8	1080 ± 64	700 ± 146	9 ± 3	45.6 ± 1.4	85.9 ± 1.1
RP-8	208.8 ± 20.78	190 ± 18.3	1100 ± 67.63	1430 ± 261	10 ± 3	44.6 ± 1.26	86.7 ± 0.32

). The low density of paper from the IAPS Goldenrod results from the low content of fillers added (8.5%), shorter fibers (0.216 µm), and the brought distribution of fiber dimensions, resulting in a poorer alignment of fibers and web connectivity [13]. The cellular structure of IAPS results in increased bulkiness and volume in the paper. The lower filler content leads to increased porosity within the paper structure. Shorter fibers have a lower aspect ratio and tend to create a less dense and more porous paper structure compared to longer fibers. The cellular structure, lower density, and improved porosity result in more voluminous papers compared to standard papers made from traditional wood fibers.

Low density also influences the surface porosity and uptake of coating suspension. The surface morphology of the analyzed papers reveals mainly a fiber network in paper from the IAPS Goldenrod (Figure 1a) and a slightly coated surface in recycled paper (Figure 1b). The recycled paper shows higher density and lower air permeability and surface roughness (Table 2). The IAPS Goldenrod paper’s surface exhibits a coarse texture, characterized by a network of fibers and pores/voids of various sizes (Figure 1a). Due to its increased porosity and free volume (Figure 1e), it readily absorbs a larger quantity of coating solution, leading to a reduced coat weight and film thickness when compared to recycled paper (Figure 2). The difference in coat weight among the coated samples of both papers is significant. At a lower wet film deposition (bars No. 1 and No. 5), the coat weight reached almost a twofold value compared to coated paper from the IAPS Goldenrod (Figure 2a). The coating speed is the important parameter influencing the coat weight. Using a lower coating speed (4 m/min) led to a higher coat weight due to the extended period taken for the coating solution to be deposited onto the paper. The viscosity of the coating solution used in bar coating plays a crucial role. The coating solution has a high viscosity, which led to a higher coat weight. The coat weight is influenced by the interaction between the coating solution and the paper substrate. A more porous and absorbent paper with a rough surface tends to result in a lower coat weight compared to a smoother, less absorbent paper. In smoother, less absorbent paper, the coating solution tends to stay on the paper’s surface for a longer time, especially when a high-viscosity solution is used, acting as a reservoir, resulting in a higher coat weight.

Rough paper has a larger surface area compared to smooth paper and can absorb more coating solution. The roughness of the paper can create capillaries that draw the coating solution into the paper structure, promoting absorption. Recycled paper with more-closed paper surfaces is less absorbent because there are fewer open pores in the surface for the coating solution to penetrate. The lower absorbency of recycled paper is clearly seen from the determined film thickness, which is, for all three different wet film deposits (6, 50, and 100 µm), higher for the recycled paper (Figure 2b). Furthermore, the values of specular gloss and ISO brightness confirm that there is no difference in gloss regardless of the coat weight of the recycled paper, whereas for the paper from the IAPS Goldenrod, the lowest film thickness resulted in a lower gloss and ISO brightness as well (Table 2).

The surface porosity of both papers was lowered with coating, especially for the paper from the IAPS Goldenrod, which has much higher air permeability compared to recycled paper for both uncoated and coated samples. From Figure 1, it is clearly seen that a film deposit of 6 µm covers the surface of both the analyzed papers. The rough surface of the paper from the IAPS Goldenrod has some influence, and some fibers are still evident in the surface topography of the coated paper (Figure 1c). The image of its cross-section (Figure 1e) confirms the thinner film layer on the surface, whereas for the recycled paper, the film layer on the surface is much thicker (Figure 1f).

To check how coating influences CMYK prints, the CIELab coordinates and optical density of the prints were determined. A low value of lightness, L* (71.8), beside positive values of color coordinates, a* (6.5) and b* (17.9), tell us that the paper from the IAPS Goldenrod has a “natural” brownish look (Table 2). This is confirmed by the high value of the yellowing index (67%), which is almost two-times higher compared to the recycled paper (40%). The difference in color between papers, delta Eab*, with a value of 17.93, is very high.

3.2. Print Characteristics

The colorimetric properties of a print represent an important criterion of print quality. In

Table 3. Colorimetric properties of prints: difference in color and optical density of CMYK prints on uncoated and coated papers.

Sample	$∆$Eab*				$\mathbf{∆}\mathit{O}\mathit{D}$
	C	M	Y	K	C	M	Y	K
GP/GP-1	39.2	20.4	30.7	15.2	0.25	0.26	0.04	0.41
GP/GP-5	39.5	19.4	27.5	17.3	0.37	0.26	0.10	0.53
GP/GP-8	43.2	22.1	33.3	18.9	0.49	0.45	0.19	0.63
RP/RP-1	28.5	24.4	21.7	20.0	0.51	0.65	0.29	0.65
RP/RP-5	27.9	24.7	22.3	19.9	0.49	0.71	0.30	0.62
RP/RP-8	30.8	26.2	23.3	21.0	0.54	0.60	0.47	0.86
GP/RP	16.7	8.4	15.2	1.4	0.06	0.12	0.15	0.03
GP-1/RP-1	4.0	9.2	1.2	4.3	0.19	0.28	0.09	0.21
GP-5/RP-5	2.9	10.9	5.9	2.2	0.10	0.33	0.05	0.07
GP-8/RP-8	2.0	7.3	1.2	1.6	0.09	0.20	0.01	0.12

, the values of delta Eab* and delta OD are given. Delta Eab*, which represents the difference between the CMYK colors printed on the uncoated paper and the CMYK colors printed on the coated papers, is presented, as well as the difference between the color prints on both uncoated papers. The optical density of print is usually the only parameter, which is measured during the printing process. Delta OD represents the difference between the optical density of the CMYK color printed on the uncoated and coated papers. It is evident that coating has a high influence on the colorimetric properties of prints, as expected. The white color of the coating solution covers the natural color of the base paper and influences how color and tonal values appear when printed.

On whiter paper, prints achieve higher contrast as well as a wider gamut of color. On coated paper, the ink settles on the surface and the color is deeper and more vibrant compared to uncoated paper, on which the colors are more dull. From Table 3, it is seen that the difference delta Eab* is the highest for cyan (C) and the lowest for black (K), meaning that high yellowness has the biggest influence on cyan prints. For all CMYK prints on both types of paper, the highest color difference is obtained for the highest coat weight, the correlation coefficient between film thickness and color change being mostly around 0.9. Nevertheless, the influence of film thickness on the change in color is quite low. A comparison of the colorimetric properties of the prints on both uncoated papers showed the highest color difference for cyan and yellow, as the color of the paper has the highest influence on these two colors. On coated papers, the color difference is noticeable, though small, except on magenta (M) prints, where a very obvious difference is seen (Table 3). The results of the optical density measurements confirm the results of the colorimetric measurements. Usually for inkjet prints, all colors at full 100% coloration exceed an optical density value of 1.0, except for lighter colors, which is also the case for recycled paper, for which only on yellow prints the value is below 1. Opposingly, on the CMYK prints on the IAPS Goldenrod paper, only the black prints exceeded an optical density value of 1.0, whereas the CMY prints had a lower value (except for the highest coat weight, where only yellow prints stayed below 1). With coating, the optical density increased, and the difference between both types of paper is small, the largest being on magenta prints.

With the image analysis, the ink bleeding, dot gain, and typographic tonal density (TTD) were measured. For the analysis, a black capitalized letter, “E”, was used in the typeface Times New Roman, size 32 pt, and two numeral 8s in the typeface Arial, size 26 pt, one printed in black color on the yellow background, the second printed in yellow color on the black background (Figure 3).

The ink bleeding evaluation was based on the measurements of the area (mm²) and perimeter (mm) of a selected printed element that were compared with the measurements of the original, i.e., its undistorted digital form. In the visualization of information, typographic tonal density has a significant impact. The TTD is the coverage of a typographic element with printing ink printed on the substrate and can vary due to changes in various letter characteristics. Differences in the TTD influenced by stroke thickness can be particularly important in small letters as they greatly affect text legibility [29]. The results showed that all the TTD values were higher compared to the digital form, as ink bleeding occurs during printing, leading to an increase in the area of printed elements. When printing on uncoated paper, the dot gain was higher for the recycled paper compared to the paper from the IAPS Goldenrod (

Table 4. Image analysis of prints: increase in halftone dot value compared to reference element.

Sample	Increase in Half Dot (%)			TTD (%)
	Black/White (E)	Black/Yellow (8)	Yellow/Black (8)	Black/White (E)	Black/Yellow (8)	Yellow/Black (8)
GP	1.00	1.07	2.15	24.44	28.43	29.51
GP-1	1.44	9.91	1.80	24.88	37.27	29.16
GP-5	1.36	14.55	0.69	24.80	41.91	28.05
GP-8	1.94	16.63	1.53	25.38	43.99	28.89
RP	4.66	3.03	1.17	28.10	30.39	28.53
RP-1	2.69	15.64	2.47	26.13	43.00	28.93
RP-5	1.42	16.99	3.08	24.86	44.36	30.44
RP-8	1.75	20.39	2.15	25.18	47.76	29.52

) because of its higher permeability and absorbency, though the difference was small. On denser recycled paper with a more-closed surface, the same amount of printing ink led to more spreading and consequently increased the surface area of the elements (Figure 3a). The same behavior was also observed on the coated papers regardless of film thickness, and the ink bleeding was highest for the coated recycled papers (Table 4).

Adding the coating had the opposite effect on the paper from the IAPS Goldenrod compared to the recycled paper when printing a black element on a white background. On the paper from the IAPS Goldenrod, the surface area of the elements increased with the addition of the coating (the smallest increase among the coated samples was observed for the wet film deposit of 50 microns, with a dot gain of 1.36% compared to uncoated paper, as seen in Table 4). However, on the recycled paper, the surface area decreased (the best results were also seen for the wet film coating deposit of 50 µm, with a dot gain of 1.42% compared to uncoated paper, where the dot gain was 4.66%). The reduced spreading of the black ink and the sharper lines of the printed elements on the recycled paper can be explained by the higher amount of coating on its surface, as less coating penetrates into the paper’s interior structure.

A similar phenomenon was observed when printing a yellow element on a black background, where the effect of the coating was again the opposite for both papers. This time, the addition of the coating positively affected the print quality for the paper from the IAPS Goldenrod, as the surface area of the elements decreased after adding the coating. The best results were seen on the wet film deposit of 50 µm, with a dot gain of only 0.69% (compared to uncoated paper, where the dot gain was 2.15%), which is also seen in Figure 3d. This also corresponds to the surface properties of the papers. However, the addition of the coating had a negative impact on the print quality of the recycled paper, as the surface area of the elements slightly increased (the smallest increase among the coated samples was observed for the wet film deposit of 100 µm, with a dot gain of 2.15%) (Table 4).

As also seen from Figure 3, the differences when printing black on white or yellow on black on the coated papers in the TTD and dot gain are quite small, only a few percent. In addition, the difference between both types of coated paper is minor. When printing a black element on a yellow background, the interaction between the printing inks and coating significantly increased the surface area of the elements for both papers. The larger the coat weight applied, the higher the inter-color bleeding and the greater the dot gain. The inks in inkjet printing are designed to be printed on adjacent areas of paper. Color-to-color bleed between the adjacent colors in the image resulting in undesirable blurring and feathering can happen when the inks have different structures. Black ink contains the pigment carbon black, whereas yellow ink contains a colorant that is fully dissolved and suspended in liquid. Ink properties such as the surface tension and viscosity of the inks, the dry time of the inks, and interactions between the inks influence these phenomena [30].

4. Conclusions

The research on the print quality of coated paper from Solidago gigantea (Giant Goldenrod) gives new insight into the use of alternative materials for printing, stimulating sustainability, and the circular economy in the papermaking and printing industries. The study revealed that coating reduces the high differences in CMYK prints on uncoated papers, resulting in similar print quality on both the analyzed substrates, regardless of their distinct surface and optical properties. The recommended amount of coating for paper from the IAPS Goldenrod is a wet film deposit of 50 µm. Moreover, the minor distinction observed in print quality between the coated paper from the IAPS Goldenrod and the recycled paper highlights the promising potential of IAPS-based paper in different applications. Enhancing the surface smoothness of coated papers could be the key to optimizing print quality further.

Due to the declining recycling rate and the lower quality of collected papers for recycling, the paper from the IAPS Goldenrod presents itself as a sustainable alternative to recycled paper. Its inherent qualities—such as recyclability, biodegradability, absence of fiber bleaching, and avoidance of precoating, represent a conscientious approach to using environmentally friendly materials for printing. Notably, our findings underscore the suitability of paper from the IAPS Goldenrod as a viable replacement for recycled paper in specific applications, such as packaging, advertising mail, mass-market paperback book editions, newspaper adds, leaflets, and flyers.

This study gives novel insights into the utilization of alternative materials in the printing industry, fostering sustainability and the circular economy. Importantly, the research findings emphasize the suitability of IAPS Goldenrod paper as a practical replacement for recycled paper in specific applications. By highlighting these applications, the study not only identifies a sustainable alternative but also provides a roadmap for the industry to make environmentally responsible choices without compromising functionality or quality.