PAPEL SUSTENTÁVEL NÃO REVESTIDO, PROCESSO DE OBTENÇÃO E USO DO MESMO

Description

1 / 11 Uncoated sustainable paper, production process and use. OF THE SAME FIELD OF THE INVENTION

[001] The present invention pertains to the field of paper and pulp, and relates to an uncoated, off-white, high-opacity sustainable paper, as well as its use in stationery products and the publishing market. The invention also relates to the process of obtaining said sustainable paper with reduced CO2 emissions and the use of chemical agents that are harmful to the environment. BACKGROUND OF THE INVENTION

[002] Uncoated paper is a type of paper without coating, whose surface is more porous and absorbent, causing it to absorb more ink, and is widely used for drawing and printing.

[003] The high absorbency of uncoated paper also gives it high-quality print characteristics, making it popular for printing catalogs, books, marketing materials, notebooks, notepads, diaries, and the like.

[004] Among the varieties of uncoated paper available on the market, Offwhite paper stands out, mainly used for book printing. Usually, Offwhite paper (yellowish tone) is offset paper (white) that undergoes treatment to result in more grayish or yellowish colors and greater opacity. Bleached cellulose with added dyes is commonly used to obtain the desired shade, as well as employing polymeric additives to improve the paper's printing properties. Petition 870250006935, dated 01 / 28 / 2025, page 12 / 27 2 / 11

[005] The yellowish tint of off-white paper reflects less light and is more opaque, which provides a more comfortable and pleasant reading experience, as well as sharper, higher-quality prints that consume less ink.

[006] In this context, document BR 11 2020 014434 7 teaches a process for manufacturing uncoated paper with improved opacity, in which polymeric additives are added to the cellulose pulp in a machine.

[007] Other documents in the state of the art are also found that teach processes for producing uncoated paper with improved printing properties, in which polymeric additives are added, such as EP 2864542 B1, BR 11 2021 008948 9 and PI 0617966 B1.

[008] However, there is a need in the state of the art for a high-opacity off-white paper that is more environmentally friendly, for example, with reduced amounts of chemical agents such as bleaches and whiteners in its production process.

[009] The off-white paper disclosed here stands out from those found in the prior art due to its enhanced color and opacity characteristics, as well as being more environmentally friendly. The production process of the paper disclosed here emits a reduced amount of CO2 and uses a low quantity of chemical additives, which makes the resulting paper more sustainable and environmentally friendly than conventionally found off-white paper on the market. SUMMARY OF THE INVENTION Petition 870250006935, dated 01 / 28 / 2025, page 13 / 27 3 / 11

[0010] The present invention relates to an uncoated, off-white, sustainable paper comprising semi-bleached cellulose pulp, mineral filler, natural polymer and one or more colorants; wherein the paper is off-white.

[0011] In an optional embodiment of the invention, the paper further comprises a dye fixative.

[0012] In a preferred embodiment of the invention, the off-white paper comprises about 60% to 85% by weight of semi-bleached cellulose pulp; about 10% to 25% by weight of mineral filler; about 3% to 5% by weight of a natural polymer; about 0.01% to 0.5% by weight of dye(s); and 0 to 0.1% by weight of dye fixative.

[0013] In one embodiment of the invention, the characteristic yellowish tone of the paper has a color space L*a*b* of: Brightness L* (D65 / 10) (No.): 84 to 86, Coordinate a* (D65 / 10) (N°): 0.7 to 1.5, Coordinate b* (D65 / 10) (N°): 12 to 14; and ΔE (N°) up to 0.7, measured in accordance with ISO 5631-2.

[0014] In one embodiment of the invention, the paper comprises two surfaces opposite each other, wherein the roughness of one surface varies from 65 to 180 ml / min and the roughness of the surface directly opposite the first varies from 80 to 320 ml / min, wherein the roughness is measured in accordance with ISO 8791-2.

[0015] In one embodiment of the invention, the paper has approximately 88% to 98% opacity, measured in accordance with ISO 2471.

[0016] In one embodiment of the invention, the cellulose is Petition 870250006935, dated 01 / 28 / 2025, p. 14 / 27 4 / 11 originating from hardwood, preferably eucalyptus.

[0017] In one embodiment of the invention, the cellulose pulp is derived from short-fiber cellulose, wherein the fibers have an average length of 0.5 to 2 mm.

[0018] In one embodiment of the invention, the mineral filler can be selected from the group consisting of Precipitated Calcium Carbonate (PCC), Natural Calcium Carbonate (GCC) and other calcium components, preferably PCC.

[0019] In one embodiment of the invention, the natural polymer comprises any type of starch.

[0020] In one embodiment of the invention, the dyes can be selected from the group consisting of violet, yellow, red dye, or a mixture thereof.

[0021] In one embodiment of the invention, paper is used for the production of books, notebooks, notepads, and other products for the publishing market.

[0022] The present invention also relates to the process for obtaining the uncoated sustainable paper disclosed herein, comprising the following steps: (a) refining of semi-bleached cellulose pulp; (b) inclusion of refined semi-bleached cellulose pulp in a storage tank; (c) preparation of a pulp by adding mineral filler, natural polymer, one or more colorants and, optionally, a color fixative to the cellulose pulp; (d) the mass obtained in step (c) enters a paper forming screen; (e) drainage of the mass over the forming screen and, in Petition 870250006935, dated 01 / 28 / 2025, page 15 / 27 5 / 11 followed by pressing, forming the paper; (f) drying of the paper; (g) paper calendering.

[0023] Considering that the off-white paper disclosed here has an opaque and yellowish color, it becomes more comfortable for reading and writing because it reflects less light on its surface. Therefore, the invention also relates to the use of the paper for application in products for the publishing market, such as books, notebooks, notepads and other related products. BRIEF DESCRIPTION OF THE FIGURES

[0024] Figure 1 represents various papers of the present invention tested in terms of coloration, according to Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention aims to optimize the environmental performance of off-white paper for supplying the publishing market, using semi-bleached cellulose instead of bleached cellulose and using dyes to obtain its characteristic color.

[0026] By using semi-bleached cellulose to obtain the uncoated paper of the present invention, the bleaching step is eliminated from the process. That is, no chemical bleaching agents are used, making the process less harmful to the environment and, consequently, more sustainable than traditional uncoated papers. The desired color and opacity characteristics are obtained from the components included in the paper disclosed herein, plus Petition 870250006935, dated 01 / 28 / 2025, page 16 / 27 6 / 11 specifically through the use of dyes for color adjustment and the addition of mineral filler to help increase opacity.

[0027] The color control of a paper comprising semi-bleached cellulose pulp is a sensitive process, requiring laboratory tests and studies to arrive at an ideal dosage of dyes applied to the semi-bleached cellulose pulp and thus guarantee the final color stability of the paper and ΔE less than 0.7.

[0028] The paper of the present invention has unique color and opacity characteristics, exhibiting a yellowish tone, and an opacity of approximately 88% to 98%, according to ISO 2471. These characteristics reduce the optical discomfort caused during reading or writing on traditional uncoated paper, making it suitable for the production of books, notebooks, and other products in the publishing industry.

[0029] The color of the paper of the present invention is defined using the CIELAB color space. This measurement distinguishes color differences by means of the L*a*b* coordinates, which indicate lightness, red / green coordinate and yellow / blue coordinate, respectively.

[0030] From the color coordinates L*a*b*, ΔE can be obtained, which indicates the perception of color with the naked eye. The smaller the ΔE, the less the perception of color tone variation, and it is desirable to obtain a ΔE less than 0.7.

[0031] The characteristic yellowish tone of the paper of the present invention has a color space L*a*b*, measured according to ISO 5631-2, of: Brightness L* (D65 / 10) (No.): 84 to 86, Petition 870250006935, dated 01 / 28 / 2025, p. 17 / 27 7 / 11 Coordinate a* (D65 / 10) (N°): 0.7 to 1.5, Coordinate b* (D65 / 10) (N°): 12 to 14;

[0032] The ΔE of the paper revealed here is less than 0.7, which indicates low perception of the paper's tonal variation. The ΔE was measured according to ISO 5631-2.

[0033] The opacity of the paper is obtained by adding mineral filler, preferably using precipitated calcium carbonate (PCC).

[0034] Furthermore, another advantageous characteristic of the paper of the present invention is that it is smooth to the touch, measured by the roughness level of the paper, measured by means of the ISO 8791-2 standard. The paper has two surfaces opposite each other, where the roughness of one surface varies from 65 to 180 ml / min and the roughness of the surface directly opposite the first varies from 80 to 320 ml / min.

[0035] In one embodiment of the invention, the uncoated sustainable paper comprises semi-bleached cellulose pulp, mineral filler, natural polymer, one or more colorants and, optionally, a colorant fixative.

[0036] In a preferred embodiment of the invention, the paper comprises about 60% to 85% by weight of semi-bleached cellulose pulp; about 10% to 25% by weight of mineral filler; about 3% to 5% by weight of natural polymer; about 0.01% to 0.5% by weight of dye(s); and 0 to 0.1% by weight of a dye fixative. The percentage by weight is based on the total paper formulation.

[0037] In a more preferred embodiment of the invention, the paper comprises about 75 to 80% by weight of semi-bleached pulp; about 15 to 20% by weight of filler. Petition 870250006935, dated 01 / 28 / 2025, p. 18 / 27 8 / 11 mineral; about 3 to 5% by weight of natural polymer; about 0.01% to 0.5% by weight of dye(s); and 0 to 0.1% by weight of a dye fixative.

[0038] The semi-bleached cellulose pulp used to obtain the paper disclosed herein is derived from hardwood, preferably eucalyptus. The cellulose pulp is derived from short-fiber cellulose, where the fibers have an average length of 0.5 to 2 mm.

[0039] In one embodiment of the invention, the mineral filler can be selected from the group consisting of Precipitated Calcium Carbonate (PCC), Natural Calcium Carbonate (GCC) and other calcium components. In a preferred embodiment, the mineral filler is Precipitated Calcium Carbonate (PCC).

[0040] In one embodiment of the invention, the natural polymer comprises any type of starch.

[0041] Semi-bleached cellulose is color-adjusted using one to three types of dyes and, optionally, a dye fixative to obtain paper with its characteristic color.

[0042] The dyes included in the role of the present invention may be selected from the group consisting of violet, yellow, red dye, or a mixture thereof.

[0043] The dye fixative optionally included in the paper of the present invention may be any dye fixative known in the state of the art.

[0044] The paper of the present invention can be used for the production of books, notebooks, pads of Petition 870250006935, dated 01 / 28 / 2025, page 19 / 27 9 / 11 notes, and other products from the publishing market.

[0045] The paper production process of the present invention begins in a machine with the receipt of semi-bleached pulp in the storage tanks. This pulp preparation stage is responsible for ensuring the best condition of the pulp, already with the other added chemicals (such as mineral filler, starch, glue, dyes, retention and drainage agents, etc.) before this mixture enters the forming screen. The semi-bleached cellulose pulp is refined to guarantee the desired physical and mechanical properties of the paper.

[0046] After the pulp containing the cellulose enters the machine, the drainage process will occur over the forming screen, followed by pressing. The paper will also pass through several heated cylinders (dryers) to further remove moisture from the paper. It also receives an external starch bath in the machine, which gives it better surface properties. At the end of the process, the paper is calendered to reduce roughness.

[0047] In one embodiment of the invention, the process for obtaining the paper disclosed herein comprises the following steps: (a) refining of semi-bleached cellulose pulp; (b) inclusion of refined semi-bleached cellulose pulp in a storage tank; (c) preparation of a pulp by adding mineral filler, natural polymer, one or more colorants and, optionally, a color fixative to the cellulose pulp; (d) the mass obtained in step (c) enters a paper forming screen; Petition 870250006935, dated 01 / 28 / 2025, page 20 / 27 10 / 11 (e) draining the pulp onto the forming screen and then pressing, forming the paper; (f) drying of the paper; (g) paper calendering.

[0048] The off-white paper production process of the present invention emits reduced amounts of CO2 and uses a low quantity of chemical additives, being a more sustainable and environmentally friendly process when compared to conventional paper production processes.

[0049] Based on a comparative life cycle analysis, the off-white paper production process described here presents notable environmental benefits compared to conventional paper processes: a 19% reduction in carbon emissions, a 12% saving in water consumption, and a 24% decrease in the consumption of fossil resources.

[0050] The invention also relates to the use of sustainable paper for application in books, notebooks, notepads, and other products in the publishing market. These products that use the paper of the present invention allow for a more comfortable and pleasant reading and writing experience by reflecting less light on their surface, due to the yellowish color and opacity of the off-white paper disclosed herein. EXAMPLES

[0051] The following examples are non-exhaustive, serving only to illustrate embodiments of the present invention without, however, limiting the scope of protection thereof. Example 1

[0052] In this example, sustainable paper does not Petition 870250006935, dated 01 / 28 / 2025, p. 21 / 27 11 / 11 coated as disclosed in the present invention was characterized in terms of coloration.

[0053] Various formulations of the paper as defined in the present invention were tested in the laboratory to adjust the ideal dye coloration, which are represented in Figure 1.

[0054] Among the paper samples tested, three were selected as preferred to assist in industrial-scale production. The color coordinates of these samples are indicated in Table 1. Table 1 Sample 11.8 Sample 11.9 Sample 11.12 Luminosity L* (D65 / 10) (N°) 84.09 84.10 84.27 Coordinate a* (D65 / 10) (N°) 0.72 0.79 0.95 Coordinate b* (D65 / 10) (N°) 12.09 12.25 12.09

[0055] The L*a*B* color spaces of the three preferred samples represent a yellowish paper color, comfortable for reading and writing. Petition 870250006935, dated 01 / 28 / 2025, page 22 / 27

Claims

1 / 3 CLAIMS 1. Uncoated sustainable paper, characterized by comprising semi-bleached cellulose pulp, mineral filler, natural polymer and one or more colorants; wherein the paper is yellowish in color.

2. Paper according to claim 1, characterized by optionally comprising a dye fixative.

3. Paper, according to claim 1 or 2, characterized by comprising: 60% to 85% by weight of semi-bleached cellulose pulp; 10% to 25% by weight of mineral filler; 3% to 5% by weight of natural polymer; 0.01% to 0.5% by weight of dye(s); and 0 to 0.1% by weight of dye fixative.

4. Paper, according to claim 1, characterized by having a yellowish tone with a color space L*a*b* of: Luminosity L* (D65 / 10) (N°): 84 to 86, Coordinate a* (D65 / 10) (N°): 0.7 to 1.5, Coordinate b* (D65 / 10) (N°): 12 to 14; and ΔE (N°) up to 0.7, measured according to ISO 5631-2.

5. Paper, according to claim 1, characterized by comprising two surfaces opposite each other, wherein the roughness of one surface varies from 65 to 180 ml / min and the roughness of the surface directly opposite the first varies from 80 to 320 ml / min, wherein the roughness is measured in accordance with ISO 87912.

6. Paper according to claim 1, characterized by having an opacity of approximately 88% to 98%, measured in accordance with ISO 2471.

7. Paper, according to claim 1 or 3, characterized in that the cellulose originates from hardwood, preferably eucalyptus.

8. Paper, according to claim 7, characterized in that the cellulose pulp is derived from short-fiber cellulose, wherein the fibers have an average length of 0.5 to 2 mm.

9. Paper, according to claim 1 or 3, characterized in that the mineral filler is selected from the group consisting of precipitated calcium carbonate (PCC), natural calcium carbonate (GCC) and other calcium components.

10. Paper, according to claim 1 or 3, characterized in that the natural polymer is starch.

11. Paper according to claim 1 or 3, characterized in that the dyes are selected from the group consisting of violet, yellow, red dye, or a mixture thereof.

12. Paper, according to any one of claims 1 to 11, characterized by being used for the production of books, notebooks, notepads, and other products for the publishing market. Petition 870250006935, dated 01 / 28 / 2025, page 24 / 27 3 / 3 13. A process for obtaining paper, as defined in any one of claims 1 to 11, characterized by comprising the following steps: (a) refining semi-bleached cellulose pulp; (b) including the refined semi-bleached cellulose pulp in a storage tank; (c) preparing a pulp by adding mineral filler, natural polymer, one or more dyes and, optionally, dye fixative to the cellulose pulp; (d) feeding the pulp obtained in step (c) into a paper forming screen; (e) draining the pulp over the forming screen and then pressing, forming the paper; (f) drying the paper; (g) calendering the paper.

14. Use of paper, as defined in any of claims 1 to 11, characterized by being for application in books, notebooks, notepads, and other products of the publishing market. Petition 870250006935, dated 01 / 28 / 2025, pp. 25 / 27

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