Method for manufacturing paper, method for manufacturing multilayer paper, paper and multilayer paper

Abstract

To provide a method for producing paper or multilayer paper using pulp containing sublimation dye components. [Solution] A method for manufacturing paper or multilayer paper by papermaking using a pulp slurry, The pulp slurry contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. A method for manufacturing paper by adding an adsorbent that adsorbs sublimation dye components to a pulp slurry and then making paper, or a method for manufacturing multilayer paper by adding an adsorbent that adsorbs sublimation dye components to at least one pulp slurry selected from among the pulp slurries that form each layer and then making multilayer paper.

Description

[Technical Field]

[0001] This invention relates to a method for manufacturing paper and multilayer paper using recycled paper pulp, and to paper and multilayer paper using recycled paper pulp. [Background technology]

[0002] The use of recycled paper pulp is required due to resource and environmental concerns, as well as the need to reuse waste paper during the manufacturing process. However, paper and cardboard made from recycled paper pulp are known to have a problem known as "hydrangea spots." Hydrangea spots are multicolored spots that appear on the surface of paper when paper or cardboard containing clumps of sublimable ink is stored at room temperature for several months. The ink clumps sublimate inside the paper, and the spots seep out. Paper and multi-layered paper that have developed hydrangea spots tend to be avoided by consumers due to their appearance, and therefore must be discarded, leading to the problem of waste paper.

[0003] It has been pointed out that the cause of clumps of sublimable ink contaminating white cardboard is the contamination of recycled paper, which is used as a raw material for recycled pulp, with sublimation transfer paper (Patent Document 1). Patent Document 1 proposes a specific sublimation transfer paper having an ink-receiving layer containing a water-soluble binder. The specific sublimation transfer paper described in Patent Document 1 allows the transfer ink to easily disperse in water along with the water-soluble binder during the disintegration process when it is collected as recycled paper and turned into recycled pulp. As a result, clumps of transfer ink are less likely to remain in the recycled pulp, and the occurrence of hydrangea spots is suppressed when recycled pulp is used as a raw material for white cardboard. However, not all of the sublimation transfer paper contained in the recycled paper is replaced with the sublimation transfer paper of Patent Document 1, and it is not possible to prevent the contamination of sublimable ink.

[0004] On the other hand, it has been proposed to analyze gas components derived from sublimable ink in gases collected from recycled paper pulp (Patent Document 2). Patent Document 2 describes how to remove sublimable ink-derived pulp by analyzing gas components in the pulp slurry obtained by disintegrating recycled paper pulp, thereby preventing its contamination of paper and multilayer paper. However, this method only removes all of the pulp containing sublimable ink, and no manufacturing method using pulp containing sublimable ink has been found. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-64187 [Patent Document 2] Japanese Patent Publication No. 2016-56488 [Overview of the project] [Problems that the invention aims to solve]

[0006] The inventors have diligently conducted research to provide a method for producing paper or multilayer paper using pulp containing sublimation dye components. [Means for solving the problem]

[0007] This invention was developed based on the discovery that when using recycled paper pulp containing sublimation dye components (recycled paper pulp containing sublimation dye components) or recycled paper pulp that may contain sublimation dye components (recycled paper pulp containing suspected sublimation dye components), the problem can be solved by adding an adsorbent. The present invention has the following aspects. [1] A method for manufacturing paper by papermaking using a pulp slurry, The pulp slurry contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. A method for producing paper by adding an adsorbent that adsorbs sublimation dye components to the pulp slurry and then making paper. [2] A method for manufacturing a multi-layer paper by multi-layer papermaking of a pulp slurry that forms at least a surface layer and a back layer, wherein at least one of the pulp slurries forming each layer contains waste paper pulp containing a sublimation dye component and / or waste paper pulp containing a suspected sublimation dye component, A method for manufacturing a multi-layer paper by multi-layer papermaking, wherein an adsorbent that adsorbs a sublimation dye component is added to at least one pulp slurry selected from the pulp slurries forming each layer. [3] A method for manufacturing paper by papermaking of a pulp slurry, a preliminary manufacturing step of papermaking a part of the pulp slurry to obtain a paper web, an evaluation step of evaluating whether a sublimation dye component is contained in the obtained paper web, a preparation step of adding an adsorbent to the remaining pulp slurry when the sublimation dye component is contained in the evaluation, a main manufacturing step of papermaking using the prepared pulp slurry, A method for manufacturing paper having the above steps. [4] A method for manufacturing a multi-layer paper by multi-layer papermaking of a pulp slurry that forms at least a surface layer and a back layer, a preliminary manufacturing step of multi-layer papermaking using a part of each layer's pulp slurry to obtain a paper web, an evaluation step of evaluating whether a sublimation dye component is contained in the obtained paper web, a preparation step of adding an adsorbent to at least one of the pulp slurries of the remaining layers when the sublimation dye component is contained in the evaluation, a main manufacturing step of multi-layer papermaking using the remaining layer pulp slurries including the prepared pulp slurry, A method for manufacturing a multi-layer paper having the above steps. [5] A method for manufacturing paper containing waste paper pulp, an evaluation step of evaluating whether a sublimation dye component is contained in the waste paper pulp, a preparation step of adding an adsorbent to the pulp slurry obtained by disintegrating the waste paper pulp when the sublimation dye component is contained in the evaluation, The main manufacturing step involves papermaking using a pulp slurry containing the prepared pulp slurry. A method for manufacturing paper having [a certain characteristic]. [6] A method for manufacturing multilayer paper having at least one layer containing recycled paper pulp, An evaluation step to determine whether the aforementioned recycled paper pulp contains sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the pulp slurry obtained by dissociating the recycled paper pulp and / or to the pulp slurry used for other layers. This manufacturing step involves multi-layer molding using pulp slurries for each layer, including the prepared pulp slurry. A method for manufacturing multilayer paper having [a specific characteristic]. [7] The method for manufacturing paper according to [1], [3], or [5], wherein the adsorbent is porous particles. [8] The method for manufacturing multilayer paper according to [2], [4], or [6], wherein the adsorbent is porous particles. Paper manufactured by the paper manufacturing method described in [9][1] or [3] or [5] or [7]. Multilayer paper manufactured by the method for manufacturing multilayer paper described in

[10] [2] or [4] or [6] or [8].

[11] The paper contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components, Furthermore, the paper contains an adsorbent that adsorbs sublimation dye components.

[12] The paper according to

[11] , wherein the adsorbent is porous particles.

[13] The paper according to

[11] or

[12] , having a coating layer on at least one side of the paper.

[14] Multilayer paper having at least a surface layer and a back layer, The aforementioned backing layer contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. A multilayer paper containing an adsorbent that adsorbs sublimation dye components in at least one layer of the surface layer and the back layer.

[15] The multilayer papermaking method according to

[14] , wherein the adsorbent is porous particles.

[16] The multilayer paper described in

[14] or

[15] , having a coating layer on at least the surface of the multilayer paper. [Effects of the Invention]

[0008] The manufacturing method of the present invention makes it possible to use recycled paper pulp containing sublimation dye components or pseudo-sublimation dye components, which were previously discarded, in the manufacture of paper and multilayer paper. The paper and multilayer paper of the present invention are capable of adsorbing sublimation dye components with an adsorbent, thereby suppressing the problem of hydrangea spots. Furthermore, by measuring the presence of an adsorbent in the paper, it is possible to identify whether or not it contains recycled paper pulp containing sublimation dye components or pseudo-sublimation dye components. [Modes for carrying out the invention]

[0009] (Paper and multilayer papermaking) In this invention, paper is manufactured by papermaking a pulp slurry. Multilayer paper is manufactured by multi-layering at least a surface pulp slurry and a backing pulp slurry. The surface layer is the layer that forms the surface of the multilayer paper. The backing layer is the layer excluding the surface layer and may consist of multiple layers. For example, the backing layer may consist of a middle layer that forms the core of the multilayer paper and a backing layer that forms the back surface. Alternatively, a surface-lower layer may be provided on the surface in contact with the surface layer, resulting in a layer configuration of surface-lower layer, middle layer, and backing layer. Or, a back-lower layer may be provided between the middle layer and the backing layer. Furthermore, the middle layer may be formed from multiple layers.

[0010] Pulp slurry is a mixture of pulp and paper layers dispersed in water for papermaking and multilayer papermaking. In addition to pulp, various anionic, nonionic, cationic, or amphoteric yield enhancers, water drainage enhancers, paper strength enhancers, internal sizing agents, and other papermaking additives may be added to the pulp slurry as needed. Other internal papermaking additives may include dyes, fluorescent whitening agents, pH adjusters, defoamers, pitch control agents, slime control agents, and other papermaking additives.

[0011] (pulp) In the present invention, the paper may contain recycled paper pulp but may also contain virgin pulp. Multilayered paper may contain recycled pulp but also virgin pulp. Furthermore, the surface layer may consist solely of virgin pulp.

[0012] Examples of raw materials for recycled paper pulp include, for example, paper that has been used once but has little printing, such as white paper, ruled white paper, extra white paper, medium white paper, and white Manila paper; printed materials such as cards, imitation paper, colored paper, Kent paper, and white art paper; colored paper that has been used once; coated printing paper; beverage cartons; and other used high-quality recycled paper such as office paper; as well as commercial medium-quality recycled paper such as tickets, medium-quality waste paper, Kent paper, and Manila paper; general medium-quality recycled paper such as newspapers, magazines, and miscellaneous paper; brown recycled paper such as cut brown paper, plain brown paper, miscellaneous bags, and cardboard; and collected paper containers and used boxes such as cardboard, white cardboard, and cardboard backings. Confidential office paper and tickets may be shredded. For the surface layer of paper or multilayer paper, it is preferable to use deinked recycled paper pulp obtained by deinking recycled paper pulp raw materials. On the other hand, for the back layer of multilayer paper, especially the middle layer, disintegrated recycled paper pulp that has not been deinked, or has low whiteness even after deinking, is mainly used.

[0013] Sublimation dye-containing recycled paper pulp is recycled paper pulp that contains sublimation dye components, and is mainly caused by the mixing of sublimation-type transfer paper with recycled paper. Sublimation-type transfer paper is classified as a prohibited item in the recycled paper standard quality specifications, but sorting is left to individual businesses, and it can still be found mixed with recycled paper. Suspected sublimation dye-containing recycled paper pulp is recycled paper pulp that may contain sublimation dye components.

[0014] Examples of virgin pulps include chemical pulps such as unbleached softwood kraft pulp (NUKP), unbleached hardwood kraft pulp (LUKP), bleached softwood kraft pulp (NBKP), bleached hardwood kraft pulp (LBKP), semi-bleached hardwood kraft pulp (LSBKP), semi-bleached softwood kraft pulp (NSBKP), hardwood sulfite pulp, and softwood sulfite pulp; and mechanical pulps such as thermomechanical pulp (TMP), chemothermetic pulp (CTMP), chemigland pulp (CGP), refinergland pulp (RGP), gland pulp (GP), pressure-pressurized stone gland pulp (PGW), and stone gland pulp (SGP).

[0015] (Adsorbent that adsorbs sublimation dye components) The adsorbent used to adsorb sublimation dye components is not particularly limited as long as it can adsorb sublimation dye components, but porous particles are preferred because they can adsorb sublimation dye components inside. For example, porous particles such as silica, zeolite, alumina, and activated carbon can be preferably used. Among these, those with a specific surface area of ​​130 m² are preferable. 2 It is preferable that it be 230m or more. 2 More preferably 330m / g or more, 2 / g is even more preferable. The larger the specific surface area, the better the adsorption of sublimation dye components. There is no particular upper limit to the specific surface area, but since it becomes an expensive material, 900m is preferable. 2 Preferably less than / g

[0016] (Coating layer) A coating layer can be provided on at least one side of paper or multilayer paper. When a coating layer is present, the sublimation dye components contained in the recycled paper pulp used are not released into the atmosphere when they sublimate, but tend to remain in the paper or multilayer paper, making it easier for hydrangea spots to occur. Therefore, paper and multilayer paper having a coating layer can fully exhibit the effects of the present invention. Examples of coating layers include pigment coating layers coated with pigment and binder, barrier layers mainly composed of resin, adhesive layers containing heat sealants, adhesives, tacks, etc., printing layers, and laminate layers, which can be appropriately selected depending on the purpose.

[0017] (First and second embodiments) The first embodiment is, A method for manufacturing paper by papermaking using a pulp slurry, The pulp slurry contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. This is a method for manufacturing paper by adding an adsorbent that adsorbs sublimation dye components to the pulp slurry and then making paper.

[0018] The second embodiment is, A method for manufacturing multilayer paper, comprising forming multiple layers of pulp slurry to create at least a surface layer and a back layer, At least one of the pulp slurries forming each of the aforementioned layers contains recycled paper pulp containing a sublimation dye component and / or recycled paper pulp containing a suspected sublimation dye component. This is a method for manufacturing multilayer paper, in which an adsorbent that adsorbs sublimation dye components is added to at least one pulp slurry selected from among the pulp slurries forming each of the aforementioned layers, and then multilayer papermaking is performed.

[0019] When using recycled paper pulp containing sublimation dye components and / or pseudo-sublimation dye components in the manufacture of paper and multilayer paper, an adsorbent that adsorbs the sublimation dye components should be used in combination. In the case of paper, the adsorbent is added to the pulp slurry. In the case of multilayer papermaking, it is preferable to add it to the pulp slurry containing pseudo-sublimation dye components. Alternatively, it may be added to the pulp slurry of other layers.

[0020] The amount of adsorbent added is not particularly limited as long as it is an amount that produces the effects of the present invention. If the specific surface area of ​​the adsorbent used is small, it is necessary to increase the amount added, and if the specific surface area is large, it is possible to decrease the amount added. As a guideline, it is about 0.1 to 30 parts per 100 parts of paper or paper layer pulp. Insufficient addition will not suppress the problem of hydrangea spots, and excessive addition will reduce the paper strength. In the case of multilayer papermaking, it may be added to the pulp slurry for multiple layers.

[0021] Furthermore, the color tone may be adjusted by adding a coloring agent to the pulp slurry for paper or the pulp slurry for the surface layer. Known coloring pigments and dyes can be used as coloring agents. For example, by using a coloring agent, it is possible to suppress the shift in the color tone of paper and multilayer paper caused by the addition of adsorbents. Alternatively, by using a coloring agent, it is possible to distinguish between products containing recycled paper pulp containing pseudo-sublimation dye components and products that do not contain recycled paper pulp containing pseudo-sublimation dye components.

[0022] (Third and fourth embodiments) The third embodiment is, A method for manufacturing paper by papermaking using a pulp slurry, A preliminary manufacturing step in which a portion of the pulp slurry is made into paper to obtain a paper product, An evaluation step to assess whether the obtained paper samples contain sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the remaining pulp slurry. The main manufacturing step involves papermaking using the prepared pulp slurry. This is a method for manufacturing paper having [a certain characteristic].

[0023] The fourth embodiment is, A method for manufacturing multilayer paper, comprising forming multiple layers of pulp slurry to create at least a surface layer and a back layer, A preliminary manufacturing step to obtain paper by multi-layer papermaking using a portion of each of the aforementioned layers of pulp slurry, An evaluation step to assess whether the obtained paper samples contain sublimation dye components. If the evaluation contains sublimation dye components, the preparation step involves adding an adsorbent to at least one of the pulp slurries of the remaining layers. The main manufacturing step involves multi-layer molding using the remaining pulp slurries, including the prepared pulp slurry. This is a method for manufacturing multilayer paper having [a specific characteristic].

[0024] When it is unclear whether recycled paper pulp containing sublimation dye components is mixed in with the paper or multilayer paper being manufactured, this method involves first manufacturing the paper or multilayer paper, evaluating whether it contains sublimation dye components, and then proceeding with the manufacturing process. If it is found to contain sublimation dye components, the paper or multilayer paper is manufactured using recycled paper pulp suspected of containing sublimation dye components.

[0025] (Provisional manufacturing step) In the production of paper and multilayer paper, a portion of the pulp slurry used for paper production, or a portion of the pulp slurry for each layer used in the production of multilayer paper, is taken out to produce a preliminary batch of paper or multilayer paper. This preliminary batch can be produced by hand, but it can also be produced using an actual paper machine or multilayer paper machine.

[0026] (Evaluation Steps) The obtained paper sheets or multi-layered paper sheets are evaluated to determine whether they contain sublimation dye components. The evaluation method is not particularly limited as long as it can determine whether or not sublimation dye components are present. For example, the obtained paper sheets can be heat-treated and the resulting sublimation gas can be analyzed. The gas to be analyzed is described in Patent Document 2. Alternatively, the obtained paper sheets can be heat-treated and evaluated to see if spots appear. For example, the obtained paper sheets can be placed between two press plates in a heat transfer press machine with the upper and lower press plates heated to 180°C, heat-pressed at a pressure of 6 MPa for 15 minutes, left at room temperature for 10 minutes, and evaluated by visually observing whether spots appear on the surface. In the case of paper sheets without a coating layer, it is preferable to evaluate them by placing coated paper or the like on one side of the paper sheet so that the sublimation dye components are not released into the atmosphere. Alternatively, the method described in the "Evaluation Test" below can be used. This method is preferred because it is simple.

[0027] "Evaluation Test" The obtained paper samples are heat-treated in a hot air dryer set to an internal temperature of 165°C for 15 minutes, then left at room temperature for 10 minutes, and evaluated by visually observing whether spots appear on the surface. For paper samples without a coating layer, it is recommended to place coated paper or similar material on one side of the sample to prevent the sublimation dye components from being released into the atmosphere during evaluation. If spots appear during the evaluation test, it is determined that sublimation dye components are present.

[0028] (Preparation step) If the evaluation indicates the presence of sublimation dye components, it is determined to be recycled paper pulp containing suspected sublimation dye components, and an adsorbent is added to the remaining pulp slurry. In the case of paper, the adsorbent is added to the pulp slurry. In the case of multilayer papermaking, the adsorbent is added to at least one pulp slurry of each of the remaining layers. It may also be added to the remaining pulp slurry of multiple layers.

[0029] The amount of adsorbent added is not particularly limited as long as it is an amount that produces the effects of the present invention. If the specific surface area of ​​the adsorbent used is small, it is necessary to increase the amount added, and if the specific surface area is large, it is possible to decrease the amount added. As a guideline, it is about 0.1 to 30 parts per 100 parts of paper or paper layer pulp. Insufficient addition will not suppress the problem of hydrangea spots, and excessive addition will reduce the paper strength. In the case of multilayer papermaking, it may be added to the pulp slurry for multiple layers.

[0030] Alternatively, the proportion of sublimation dye components may be reduced by adding separately prepared recycled paper pulp that does not contain sublimation dye components to the pulp slurry containing recycled paper pulp containing suspected sublimation dye components.

[0031] Furthermore, the color tone may be adjusted by adding a coloring agent to the pulp slurry for paper or the pulp slurry for the surface layer. Known coloring pigments and dyes can be used as coloring agents. For example, by using a coloring agent, it is possible to suppress the shift in the color tone of paper and multilayer paper caused by the addition of adsorbents. Alternatively, by using a coloring agent, it is possible to distinguish between products containing recycled paper pulp containing pseudo-sublimation dye components and products that do not contain recycled paper pulp containing pseudo-sublimation dye components.

[0032] If the evaluation step determines that the product does not contain sublimation dye components, it is acceptable to proceed with manufacturing the product as one that does not contain sublimation dye components.

[0033] (This is the manufacturing step) For paper, the prepared pulp slurry is used to make paper in a paper machine. For multilayer paper, the prepared pulp slurry, along with the remaining pulp slurries for each layer, is used to make multilayer paper in a multilayer paper machine.

[0034] If an actual machine (paper machine or multilayer paper machine) is used in the preliminary manufacturing step, the production of paper or multilayer paper will continue between the evaluation step and the adjustment step. In this case, paper or multilayer paper that does not contain an adsorbent will be handled separately from the product. For example, the product could be offered to customers who acknowledge the possibility of hydrangea spotting, or it could be disintegrated again and the disintegrated pulp used as recycled paper pulp containing pseudo-sublimation dye components to manufacture paper or multilayer paper, or used as fuel, or simply disposed of. The preliminary manufacturing step is preferable because it reduces the amount of waste and other discarded materials.

[0035] (Fifth and sixth embodiments) The fifth embodiment is, A method for manufacturing paper containing recycled paper pulp, An evaluation step to determine whether the aforementioned recycled paper pulp contains sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the pulp slurry obtained by dissociating the recycled paper pulp. The main manufacturing step involves papermaking using a pulp slurry containing the prepared pulp slurry. This is a method for manufacturing paper having [a certain characteristic].

[0036] The sixth embodiment is, A method for manufacturing multilayer paper having at least one layer containing recycled paper pulp, An evaluation step to determine whether the aforementioned recycled paper pulp contains sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the pulp slurry obtained by dissociating the recycled paper pulp and / or to the pulp slurry used for other layers. This manufacturing step involves multi-layer molding using pulp slurries for each layer, including the prepared pulp slurry. This is a method for manufacturing multilayer paper having [a specific characteristic].

[0037] This method involves confirming whether the recycled paper pulp contains sublimation dye components before manufacturing paper or multilayer paper using recycled paper pulp.

[0038] (Evaluation Steps) The obtained paper sheets or multi-layered paper sheets are evaluated to determine whether they contain sublimation dye components. The evaluation method is not particularly limited as long as it can determine whether or not sublimation dye components are present. For example, the obtained paper sheets can be heat-treated and the resulting sublimation gas can be analyzed. The gas to be analyzed is described in Patent Document 2. Alternatively, the obtained paper sheets can be heat-treated and evaluated to see if spots appear. For example, the obtained paper sheets can be placed between two press plates in a heat transfer press machine with the upper and lower press plates heated to 180°C, heat-pressed at a pressure of 6 MPa for 15 minutes, left at room temperature for 10 minutes, and evaluated by visually observing whether spots appear on the surface. In the case of paper sheets without a coating layer, it is preferable to evaluate them by placing coated paper or the like on one side of the paper sheet so that the sublimation dye components are not released into the atmosphere. Alternatively, the method described in the "Evaluation Test" below can be used. This method is preferred because it is simple.

[0039] "Evaluation Test" The obtained paper samples are heat-treated in a hot air dryer set to a temperature of 165°C for 15 minutes, then left at room temperature for 10 minutes, and evaluated by visually observing whether spots appear on the surface. For paper samples without a coating layer, it is recommended to place coated paper or similar material on one side of the sample to prevent the release of sublimation dye components into the atmosphere during evaluation. If spots appear during the evaluation test, it is determined that sublimation dye components are present.

[0040] (Preparation step) If sublimation dye components are found in the evaluation, the material is treated as recycled paper pulp containing sublimation dye components, and an adsorbent is added to the pulp slurry obtained by dissociating the pulp sheet. In the case of paper, the adsorbent is added to the pulp slurry. In the case of multilayer papermaking, the adsorbent is added to at least one pulp slurry of each layer. It may also be added to the pulp slurry of other layers.

[0041] The amount of adsorbent added is not particularly limited as long as it is an amount that produces the effects of the present invention. If the specific surface area of ​​the adsorbent used is small, it is necessary to increase the amount added, and if the specific surface area is large, it is possible to decrease the amount added. As a guideline, it is about 0.1 to 30 parts per 100 parts of paper or paper layer pulp. Insufficient addition will not suppress the problem of hydrangea spots, and excessive addition will reduce the paper strength. In the case of multilayer papermaking, it may be added to the pulp slurry for multiple layers.

[0042] Furthermore, it is possible to reduce the proportion of sublimation dye components by adding separately prepared recycled paper pulp that does not contain sublimation dye components to the pulp slurry containing sublimation dye components.

[0043] Furthermore, a coloring agent may be added to the pulp slurry for paper or the pulp slurry for the surface layer to adjust the color tone. Known coloring pigments and dyes can be used as coloring agents. For example, by using a coloring agent, it is possible to suppress the shift in the color tone of paper and multilayer paper caused by the addition of adsorbents. Alternatively, by using a coloring agent, it is possible to distinguish between products containing recycled paper pulp containing pseudo-sublimation dye components and products that do not contain recycled paper pulp containing pseudo-sublimation dye components.

[0044] If the evaluation determines that the product does not contain sublimation dye components, it is acceptable to manufacture it as a product that does not contain sublimation dye components.

[0045] (This is the manufacturing step) For paper, the prepared pulp slurry is used to make paper in a paper machine. For multilayer paper, the prepared pulp slurry, along with the remaining pulp slurries for each layer, is used to make multilayer paper in a multilayer paper machine.

[0046] (Paper manufactured according to each embodiment, multilayer paper) The paper produced according to the first, third, and fifth embodiments is paper that suppresses the problem of hydrangea spots. In addition, the products produced according to each embodiment will include paper containing sublimation dye component-containing pulp or pseudo-sublimation dye component-containing pulp, and ordinary paper that does not contain sublimation dye component-containing pulp. By checking for the presence or absence of adsorbent in the paper, it is possible to distinguish whether the paper contains sublimation dye component-containing pulp or pseudo-sublimation dye component-containing pulp, or whether it does not contain sublimation dye component-containing pulp, during the manufacturing process.

[0047] The multilayer paper manufactured according to the second, fourth, and sixth embodiments is a multilayer paper that suppresses the problem of hydrangea spots. In addition, the products produced according to each embodiment will include multilayer paper containing sublimation dye component-containing pulp or pseudo-sublimation dye component-containing pulp, and multilayer paper that does not contain sublimation dye component-containing pulp. However, by checking the presence or absence of adsorbent in the multilayer paper, it is possible to distinguish whether the multilayer paper contains sublimation dye component-containing pulp or pseudo-sublimation dye component-containing pulp or whether it does not contain sublimation dye component-containing pulp during the manufacturing process.

[0048] For the paper or multilayer paper obtained in each embodiment, it is preferable to perform the evaluation steps described in the third or fourth embodiment again. If spots due to sublimation dye components appear during evaluation, it is preferable to further increase the amount of adsorbent and proceed with production.

[0049] (The 7th and 8th embodiments) The 7th embodiment is paper containing pulp containing a sublimable dye component and / or waste paper pulp containing a suspected sublimable dye component, and further, paper containing an adsorbent that adsorbs the sublimable dye component. The 8th embodiment is multi-layer paper having at least a surface layer and a back layer, wherein the back layer contains pulp containing a sublimable dye component and / or waste paper pulp containing a suspected sublimable dye component, and the multi-layer paper contains an adsorbent that adsorbs the sublimable dye component in at least one of the surface layer and the back layer.

[0050] The adsorbent that adsorbs the sublimable dye component is not particularly limited as long as it can adsorb the sublimable dye component, but porous particles are preferable because the sublimable dye component can be adsorbed inside. For example, porous particles such as silica, zeolite, alumina, and activated carbon can be preferably used. Among them, the specific surface area is preferably 130 m 2 / g or more, more preferably 230 m 2 / g or more, and even more preferably 330 m 2 / g. The larger the specific surface area, the better the adsorbability of the sublimable dye component. There is no particular upper limit to the specific surface area, but since it becomes an expensive material, it is preferably 900 m<00000(...)​​​​​​​​​​More than 200g / m 2 The following applies. The basis weight can be adjusted as needed depending on the application. There are no particular restrictions on the basis weight of multi-layered paper, such as 100g / m². 2 More than 1000g / m 2 The following applies. The basis weight can be adjusted as needed depending on the application. Basis weight can be measured in accordance with JIS P8124.

[0053] Multilayer papermaking allows for a higher basis weight and thus a greater use of recycled pulp. Therefore, since hydrangea spotting is more likely to occur, the advantages of this invention are significant. The following describes multilayer papermaking.

[0054] Multilayered paper has at least a front layer and a back layer, but the back layer may have multiple layers. For example, it can have a front layer, a middle layer, and a very back layer; a front layer, a lower front layer, a middle layer, and a very back layer; or a front layer, a lower front layer, a middle layer, a lower back layer, and a very back layer. The middle layer may also consist of multiple layers. The number of layers in multilayered paper is determined by the paper machine used for production. For example, a 7-layer paper machine cannot produce 8 or more layers.

[0055] The surface layer typically uses pulp with high whiteness. Examples of high-whiteness pulp include virgin pulp and deinked recycled pulp. The basis weight of the surface layer is 15-90 g / m². 2 It is preferable to use 25-70 g / m². 2 It is preferable to do so. If the basis weight of the surface layer is above the preferred lower limit, the dark appearance of the middle layer can be sufficiently concealed. Furthermore, if the basis weight of the surface layer is below the preferred upper limit, swelling during papermaking is less likely to occur.

[0056] When a sub-layer is provided, the pulp constituting the sub-layer should have a higher whiteness than the pulp in the middle layer, but a lower whiteness than the pulp in the top layer. Deinked pulp may be used as part or all of the pulp constituting the sub-layer. The basis weight of the sub-layer should be 15-90 g / m². 2Preferably, this would be 25-75 g / m². 2 It is preferable to do so. If the basis weight of the lower layer is above the preferred lower limit, it can adequately conceal the dark appearance of the middle layer, along with the surface layer. Furthermore, if the basis weight of the lower layer is below the preferred upper limit, it helps to suppress swelling during papermaking.

[0057] The middle layer is usually composed of multiple layers, but it may also be a single layer. If the middle layer is composed of multiple layers, the pulp that makes up each layer may all be the same or may be different. The middle layer is a layer sandwiched between at least the surface and back layers, and therefore, it is generally made from the lowest-grade pulp among the layers that make up the base paper. Examples include disintegrated pulp from newspapers, magazines, tickets, medium-quality scrap paper, tea imitation, corrugated cardboard, backing paper, land deeds, and balls. The total basis weight of the middle layer is adjusted as appropriate according to the required thickness for the application of the coated paperboard, but the basis weight per layer is 15-250 g / m². 2 It is preferable to do so, with a value of 25-230 g / m². 2 It is preferable to do so.

[0058] When a sub-back layer is provided, the pulp used for the sub-back layer should have a higher degree of whiteness than the pulp used for the middle layer, but a lower degree of whiteness than the pulp used for the back layer. The sub-back layer may use the same pulp used for the top layer and sub-top layer, but usually, a lower-grade recycled paper, i.e., recycled paper containing a large amount of medium-density fibers, is used compared to the top layer. For example, unbleached and deinked recycled paper pulp from newspapers, magazines, colored paper, and balls is commonly used. The basis weight of the lower layer is 15-90 g / m². 2 Preferably, this would be 25-80 g / m². 2 It is preferable to do so. If the basis weight of the lower back layer is above the preferred lower limit, it can adequately conceal colored foreign matter in the middle layer along with the back layer. Furthermore, if the basis weight of the lower back layer is below the preferred upper limit, sufficient paper layer strength can be obtained.

[0059] While the back layer does not require the same level of whiteness as the top layer, it is visible to the human eye, so typically, pulp with a higher degree of whiteness than the middle layer, or pulp that has been treated to remove dust and foreign matter, is used. Pulp derived from shredded office paper may also be included. Pulp obtained by disintegrating shredded office paper has a relatively high degree of whiteness even without deinking or bleaching, so it is preferable to incorporate it into the back layer. The basis weight of the backing layer is 15-90 g / m². 2 It is preferable to use 25-70 g / m². 2 It is more preferable to do so. The basis weight of the middle layer is adjusted as appropriate according to the thickness required for the application of the multi-layered paper. If the basis weight of the backing layer is above the preferred lower limit, colored foreign matter in the middle layer can be sufficiently concealed. Furthermore, if the basis weight of the backing layer is below the preferred upper limit, sufficient paper layer strength can be obtained.

[0060] The paper of the present invention can be used as printing paper, packaging paper, and information paper. The multilayer paper of the present invention can be used as cardboard, white cardboard, coated white cardboard, etc. Furthermore, the paper and multilayer paper of the present invention can be laminated together. That is, they can be laminated together using an adhesive such as starch, such as paper and paper, paper and paper and paper, paper and multilayer paper, or multilayer paper and multilayer paper. They can also be laminated with films, synthetic papers, etc.

[0061] (Coating layer) Furthermore, a pigment coating layer containing a pigment and a binder can be provided on at least one side of the paper or multilayer paper of the present invention. Providing the coating layer improves printability. A pigment coating layer can also be provided on the other side of the paper or multilayer paper. Providing the pigment coating layer improves printability. In the case of multilayer paper, providing a pigment coating layer on the surface further improves printability.

[0062] Furthermore, paper and multilayer paper may be provided with coating layers other than the pigment coating layer. For example, various coating layers such as barrier layers mainly composed of resin, heat sealants, adhesives, tacks, etc., printing layers, and laminating layers can be appropriately used depending on the purpose. [Examples]

[0063] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the following description.

[0064] <Examples> "Preparation of pulp slurry" For the surface layer, a pulp slurry was used, consisting of 100 parts by mass of pulp with a whiteness of 85%, made by mixing 80% by mass of deinked pulp obtained by deinking high-quality recycled paper (recovered from printing and bookbinding companies) and 20% by mass of bleached hardwood kraft pulp, to which 11 parts by mass of light calcium carbonate (product name "Tamapearl TP121-6S", manufactured by Okutama Kogyo Co., Ltd.) was added. Pulp slurry for the subsurface layer: 100 parts by mass of deinked recycled magazine pulp with a whiteness of 70% was used. Pulp slurry for the middle layer: Made using recycled magazine pulp with a whiteness of 40%. Pulp slurry for the backing layer: A pulp with a whiteness of 51% was used, blended in the following proportions: 50% by mass of recycled newspaper, 40% by mass of recycled magazines, and 10% by mass of pulp derived from shredded office waste paper. It is unclear whether the recycled paper pulp contains pulp derived from sublimation transfer paper.

[0065] "Multilayered papermaking (handmade)" Using the pulp slurry for each layer obtained from the above pulp slurry preparation, the top layer, subtop layer, middle layer (three layers), and backmost layer were formed using a circular hand-operated papermaking machine and then stacked to create multi-layered paper. Here, the basis weight of the top layer was 40 g / m². 2 The basis weight of the lower layer is 45 g / m². 2 The total basis weight of the middle layer is 135 g / m². 2 The basis weight of the back layer is 45 g / m² 2 The dough was handmade to achieve this result.

[0066] "Evaluation Test 1" Three sets of the resulting 16cm diameter multilayer paper were prepared, and commercially available A2 coated paper (basis weight 79g / m²) was used. 2 The samples were stacked and then heated in a hot air dryer set to an internal temperature of 165°C for 15 minutes. After that, they were left at room temperature for 10 minutes, and the surface was visually inspected to see if any spots had formed. As a result, the formation of hydrangea-like spots was observed.

[0067] "Readjustment of pulp slurry" Pulp slurry for the subsurface layer: 100 parts by mass of deinked recycled magazine pulp with a whiteness of 70%, with synthetic silica (product name: Mizukasorb C-1, manufactured by Mizusawa Chemical Industry Co., Ltd., particle size 10 μm, specific surface area 400 m²) as an adsorbent. 2 It contains 4 parts by mass of ( / g).

[0068] "Multilayered papermaking (handmade)" Using the pulp slurry for each layer obtained from the above pulp slurry preparation, the top layer, subtop layer, middle layer (three layers), and backmost layer were formed using a circular hand-operated papermaking machine and then stacked to create multi-layered paper. Here, the basis weight of the top layer was 40 g / m². 2 The basis weight of the lower layer is 45 g / m². 2 The total basis weight of the middle layer is 135 g / m². 2 The basis weight of the back layer is 45 g / m² 2 The dough was handmade to achieve this result.

[0069] "Evaluation Test 2" Three sets of the resulting 16cm diameter multilayer paper were prepared and evaluated again under the same conditions as in "Evaluation Test 1" above. As a result, no hydrangea spots were observed.

[0070] "Multi-layer papermaking (actual machine)" Using the pulp slurry for the surface, middle, and back layers obtained by the above-mentioned pulp slurry preparation, and the pulp slurry for the lower surface layer obtained by the above-mentioned pulp slurry re-preparation, a multi-layer paper having a surface layer, a lower surface layer, a middle layer (two layers), and a back layer was obtained using a multi-layer papermaking machine. Here, the basis weight of the surface layer was 40 g / m². 2 The basis weight of the lower layer is 45 g / m². 2 The total basis weight of the middle layer is 190 g / m².2 The basis weight of the back layer is 45 g / m² 2 The paper was printed in a multi-layered manner to achieve this result.

[0071] On the surface of the resulting multilayer paper, apply the following undercoat liquid at a dry weight of 10 g / m² using a rod coater. 2 The primer layer was formed by coating and drying in the manner described below. On the primer layer, the following topcoat liquid was applied using a blade coater at a dry weight of 10 g / m². 2 The paper was coated and dried in such a manner to form a topcoat layer. After the topcoat layer was formed, the paper was passed through a soft calender with a metal roll surface temperature of 200°C and 2 nips to obtain multilayer paper (coated white cardboard) with a coated layer.

[0072] (Preparation of primer coating solution) 100 parts of heavy calcium carbonate (product name: FMT-OP, manufactured by Fimatec) were used as the pigment, and 0.05 parts of sodium polyacrylate were added as a dispersant to 100 parts of pigment. A pigment dispersion with a solid content of 72% was prepared using a Koreth disperser. Next, 3 parts of oxidized starch (product name: Oji Ace Y, manufactured by Oji Corn Starch Co., Ltd.) and 14 parts of styrene-butadiene copolymer latex A (product name: T2548A, manufactured by JSR, glass transition temperature -34℃, average particle size 140nm) were added to this pigment dispersion on a solid content basis per 100 parts of pigment, to obtain a primer coating solution with a final solid content of 62%.

[0073] (Preparation of coating liquid for the topcoat layer) As pigments, 70 parts of heavy calcium carbonate (product name: FMT-OP, previously mentioned), 25 parts of kaolin (product name: Ultra White 90, manufactured by BASF, average particle size 0.32 μm), and 5 parts of titanium dioxide (product name: KA-100, manufactured by Cosmo Chemical Co., Ltd., Korea) were used. As a dispersant, 0.1 parts of sodium polyacrylate was added per 100 parts of pigment, and a pigment dispersion with a solid content of 72% was prepared using a Koreth disperser. Next, to this pigment dispersion, 2 parts of oxidized starch (product name: Ace Y, previously mentioned) and 16 parts of styrene-butadiene copolymer latex B (product name: B1840, manufactured by Asahi Kasei Chemicals, average particle size 95 nm) were added on a solid content basis per 100 parts of pigment, to obtain a topcoat coating solution with a final solid content of 65%.

[0074] "Evaluation Test 3" From the obtained coated multilayer paper, evaluation samples measuring 1 m in length and 4 m in width were taken, heated in a hot air dryer set to an internal temperature of 165°C for 15 minutes, and then left at room temperature for 10 minutes. The samples were then evaluated by visually observing whether spots appeared on the surface. As a result, no hydrangea spots were observed.

[0075] According to the manufacturing method of the present invention, recycled paper pulp containing sublimation dye components and recycled paper pulp containing suspected sublimation dye components, which were previously discarded, can be used in the manufacture of paper and multilayer paper. The paper and multilayer paper of the present invention are capable of adsorbing sublimation dye components with an adsorbent, thereby suppressing the problem of hydrangea spots. Furthermore, by measuring the presence of an adsorbent in the paper, it is possible to identify whether or not the paper (multilayer paper) was manufactured with the knowledge that it contained recycled paper pulp containing sublimation dye components or pulp containing suspected sublimation dye components.

Claims

1. A method for manufacturing paper by papermaking using a pulp slurry, The pulp slurry contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. A method for producing paper by adding an adsorbent that adsorbs sublimation dye components to the pulp slurry and then making paper.

2. A method for manufacturing multilayer paper, comprising forming multiple layers of pulp slurry to create at least a surface layer and a back layer, At least one of the pulp slurries forming each of the aforementioned layers contains recycled paper pulp containing a sublimation dye component and / or recycled paper pulp containing a suspected sublimation dye component. A method for manufacturing multilayer paper, comprising adding an adsorbent that adsorbs sublimation dye components to at least one pulp slurry selected from among the pulp slurries forming each of the aforementioned layers, and then forming the multilayer paper.

3. A method for manufacturing paper by papermaking using a pulp slurry, A preliminary manufacturing step in which a portion of the pulp slurry is made into paper to obtain a paper product, An evaluation step to assess whether the obtained paper samples contain sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the remaining pulp slurry. The main manufacturing step involves papermaking using the prepared pulp slurry. A method for manufacturing paper having [a certain characteristic].

4. A method for manufacturing multilayer paper, comprising forming multiple layers of pulp slurry to create at least a surface layer and a back layer, A preliminary manufacturing step to obtain paper by multi-layer papermaking using a portion of each of the aforementioned layers of pulp slurry, An evaluation step to assess whether the obtained paper samples contain sublimation dye components. If the evaluation contains sublimation dye components, the preparation step involves adding an adsorbent to at least one of the pulp slurries of the remaining layers. The main manufacturing step involves multi-layer molding using the remaining pulp slurries, including the prepared pulp slurry. A method for manufacturing multilayer paper having [a specific characteristic].

5. A method for manufacturing paper containing recycled paper pulp, An evaluation step to determine whether the aforementioned recycled paper pulp contains sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the pulp slurry obtained by dissociating the recycled paper pulp. The main manufacturing step involves papermaking using a pulp slurry containing the prepared pulp slurry. A method for manufacturing paper having [a certain characteristic].

6. A method for manufacturing multilayer paper having at least one layer containing recycled paper pulp, An evaluation step to determine whether the aforementioned recycled paper pulp contains sublimation dye components. If the evaluation includes sublimation dye components, the preparation step involves adding an adsorbent to the pulp slurry obtained by dissociating the recycled paper pulp and / or to the pulp slurry used for other layers. This manufacturing step involves multi-layer molding using pulp slurries for each layer, including the prepared pulp slurry. A method for manufacturing multilayer paper having [a specific characteristic].

7. The method for producing paper according to claim 1, 3, or 5, wherein the adsorbent is porous particles.

8. The method for manufacturing multilayer paper according to claim 2, 4, or 6, wherein the adsorbent is porous particles.

9. Paper manufactured by the paper manufacturing method described in claim 1, 3, or 5.

10. Multilayer paper manufactured by the method for manufacturing multilayer paper according to claim 2, 4, or 6.

11. The paper contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. Furthermore, the paper contains an adsorbent that adsorbs sublimation dye components.

12. The paper according to claim 11, wherein the adsorbent is porous particles.

13. The paper according to claim 11 or 12, having a coating layer on at least one side of the paper.

14. A multilayer paper having at least a surface layer and a back layer, The aforementioned backing layer contains recycled paper pulp containing sublimation dye components and / or recycled paper pulp containing suspected sublimation dye components. A multilayer paper containing an adsorbent that adsorbs sublimation dye components in at least one layer of the surface layer and the back layer.

15. The multilayer papermaking method according to claim 14, wherein the adsorbent is porous particles.

16. The multilayer paper according to claim 14 or 15, wherein at least the surface of the multilayer paper has a coating layer.