Bale manufacturing method

Abstract

To provide a bale manufacturing method which is excellent in shape retainability of a molded bale, and is also excellent in disintegration properties of a used paper piece included in the bale.SOLUTION: A bale manufacturing method includes a molding step of compression molding a used paper piece having at least a resin layer and a paper base material layer, and obtaining a bale, wherein a basis weight of the used paper piece is 100 g / m2 or more, and water absorption for 24 hours of the used paper piece is 15% or more and 85% or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a bale. [Background technology]

[0002] In recent years, efforts to eliminate plastic have been accelerating worldwide due to growing interest in reducing waste and environmental issues. As a result, efforts are being made to change from plastic-only raw materials to paper raw materials that combine paper and plastic in order to reduce the amount of plastic used in various products. Previously, recycled paper laminated with a resin layer was considered taboo and was not reused, but with increasing interest in reducing waste and environmental issues, there is now a demand for the use of laminated recycled paper. Generally, waste paper is temporarily stored in bales for recycling.

[0003] Patent Document 1 discloses an apparatus for forming bales from compressible waste materials such as waste paper and discarded cartons. The apparatus has a substantially rectangular parallelepiped shape and includes a press housing having at least one compression chamber and a press plate that can be reciprocated in the pressing direction within the compression chamber by a drive means. Furthermore, Patent Document 2 discloses a bale press for compressing paper, cardboard, etc., which has a load chamber that receives material to be compressed and baled by a piston mechanism that reciprocates within the chamber, and a choke chamber that is formed at the outlet of the load chamber, holds the compressed material by frictional force, and presses new material against the held material by the piston mechanism. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2010-521312 [Patent Document 2] International Publication No. 1998 / 33643 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, waste paper is formed into bales using bale-forming devices such as those disclosed in Patent Documents 1 and 2, and then recycled. However, waste paper that has a resin layer in addition to a paper base layer may not be able to maintain its bale shape and may collapse. Furthermore, depending on the state of the formed bale, its disintegration properties may be insufficient, reducing its recyclability. An object of the present invention is to provide a method for producing a bale which allows the formed bale to have excellent shape retention and also allows the waste paper contained in the bale to have excellent disintegration properties. [Means for solving the problem]

[0006] The inventors have discovered that in a bale manufacturing method that includes a molding step in which waste paper pieces having at least a resin layer and a paper base layer are compressed and molded to obtain a bale, the above-mentioned problem can be solved by providing the waste paper pieces with a basis weight of a specific value or more and a water absorbency within a certain range. The present invention relates to the following [1] to [9]. [1] A method for manufacturing a bale by compressing and molding waste paper pieces having at least a resin layer and a paper base layer, wherein the basis weight of the waste paper pieces is 100 g / m 2 The method for producing a bale is as described above, wherein the water absorbency of the waste paper pieces over 24 hours is 15% or more and 85% or less. [2] The method for manufacturing a bale according to [1], wherein the folding strength of the waste paper pieces is 20 gf or more and 350 gf or less. [3] The median area of ​​the waste paper pieces is 20 cm 2 More than 200cm 2 A method for producing a veil according to [1] or [2], which is as follows: [4] Bale density is 0.3t / m 3 More than 1.0t / m 3A method for producing a bale according to any one of [1] to [3] below. [5] The method for manufacturing a bale according to any one of [1] to [4], wherein the content of the sizing agent in the paper base layer of the waste paper pieces is 0.2% by mass or more and 2.1% by mass or less. [6] The method for manufacturing a bale according to any one of [1] to [5], wherein the waste paper pieces further have a metal layer. [7] Bale forming pressure: 500kN / m 2 More than 2500kN / m 2 The method for producing a bale according to any one of [1] to [6] below. [8] The method for producing a bale according to any one of [1] to [7], further comprising a crushing step of crushing waste paper before bale formation. [9] The method for producing a bale according to any one of [1] to [8], further comprising a washing step of washing the waste paper or waste paper pieces before forming the bale. [Effects of the Invention]

[0007] According to the present invention, a method for producing a bale is provided which allows the formed bale to have excellent shape retention and also allows the waste paper pieces contained in the bale to have excellent disintegration properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Bale manufacturing method] The method for manufacturing a bale of this embodiment includes a molding step of compressing and molding waste paper pieces having at least a resin layer and a paper base layer (hereinafter also simply referred to as "waste paper pieces") to obtain a bale, and the basis weight of the waste paper pieces is 100 g / m 2 The water absorbency of the waste paper pieces for 24 hours is 15% or more and 85% or less. According to the bale manufacturing method of this embodiment, the formed bale has excellent shape retention and also has excellent disintegration properties for the waste paper pieces contained in the bale. Although the reason for this is not clear, it is thought to be as follows. Generally, waste paper pieces containing a resin layer tend to have poor defibration properties when subjected to defibration treatment because the resin layer prevents water from penetrating. 2 Since the waste paper pieces described above have a large force that causes them to return to their original expanded state even when compressed, bales containing such waste paper pieces tend to have difficulty maintaining their shape. In contrast, in the bale manufacturing method of this embodiment, the 24-hour water absorbency of the waste paper pieces is 15% or more, so when the resulting bale is recycled, water will sufficiently penetrate the waste paper pieces, which is thought to improve disintegration properties. Also, the 24-hour water absorbency of the waste paper pieces is 85% or less, so when the bale becomes moist, such as when the waste paper pieces are washed or the resulting bale is exposed to rain during storage, the shape of the bale is prevented from collapsing due to the influence of the moisture, and the shape retention of the resulting bale is thought to be improved.

[0009] The basis weight of the waste paper pieces is set to 100 g / m from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. 2 or more, and preferably 120 g / m 2 More than 600g / m 2 or less, more preferably 140 g / m 2 More than 500g / m 2 or less, more preferably 160 g / m 2 More than 400g / m 2 or less, even more preferably 180 g / m 2 More than 300g / m 2 The following is the result. The basis weight of the waste paper pieces is measured by the method described in the examples.

[0010] The 24-hour water absorbency of the waste paper pieces is 15% or more and 85% or less, preferably 30% or more and 75% or less, and more preferably 45% or more and 65% or less, from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. The water absorbency of the waste paper pieces is adjusted, for example, by the content of sizing agent in the paper base layer of the waste paper pieces. The 24-hour water absorbency of the waste paper pieces is determined from the rate of increase in the mass of the waste paper pieces when the waste paper pieces are immersed in water for 24 hours, and specifically, is determined by the method described in the examples.

[0011] (pieces of waste paper) In this embodiment, the waste paper pieces that are the raw material for the bale have at least a resin layer and a paper base layer. [Resin layer] The resin that constitutes the resin layer in the waste paper pieces is not particularly limited, but examples include polyolefins such as high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polypropylene (PP), polyesters such as polyethylene terephthalate (PET), polyamides such as ethylene-vinyl alcohol copolymer (EVOH), nylon, ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer (EMMA), styrene-acrylic copolymer, and ethylene-α-olefin copolymer. Furthermore, when the waste paper pieces have multiple resin layers, the resins that constitute each resin layer may be the same or different. Among these, from the viewpoint of recyclability, the resin constituting the resin layer is preferably one or more selected from polyolefin, ethylene-vinyl alcohol copolymer (EVOH), and ethylene-methyl methacrylate copolymer (EMMA), more preferably one or more selected from low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ethylene-methyl methacrylate copolymer (EMMA), and even more preferably one or more selected from low-density polyethylene (LDPE) and linear low-density polyethylene (LLDPE).

[0012] From the viewpoint of improving the shape retention and disintegration properties of the resulting bale, the thickness of the resin layer in the waste paper pieces is preferably 5 μm to 130 μm, more preferably 10 μm to 110 μm, even more preferably 15 μm to 90 μm, and even more preferably 20 μm to 70 μm. When the waste paper pieces have multiple resin layers, the thickness of the resin layers in the waste paper pieces refers to the total thickness of the respective resin layers.

[0013] The basis weight of the resin layer in the waste paper pieces is preferably 5 g / m from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. 2 More than 120g / m 2 Less than 10 g / m, more preferably 2 More than 100g / m 2 or less, more preferably 15 g / m 2 More than 80g / m 2 More preferably, 20 g / m or less 2 More than 60g / m 2 In addition, when a piece of waste paper has a plurality of resin layers, the basis weight of the resin layers in the piece of waste paper indicates the total basis weight of the respective resin layers.

[0014] [Paper base layer] The paper base layer is not particularly limited as long as it is a commonly used paper containing plant-derived wood pulp as a main component. Examples of wood pulp include, but are not limited to, chemical pulps such as hardwood kraft pulp (LKP), softwood kraft pulp (NKP), sulfite pulp (SP), dissolving pulp (DP), soda pulp (AP), bleached kraft pulp (BKP), unbleached kraft pulp (UKP), and oxygen-bleached kraft pulp (OKP), semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-groundwood pulp (CGP), and mechanical pulps such as groundwood pulp (GP), thermomechanical pulp (TMP), and chemi-thermomechanical pulp (CTMP). Among these, from the viewpoint of recyclability, the paper base layer preferably contains one or more selected from hardwood kraft pulp and softwood kraft pulp, more preferably one or more selected from hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood unbleached kraft pulp (NUKP) and softwood bleached kraft pulp (NBKP), and even more preferably one or more selected from hardwood bleached kraft pulp (LBKP) and softwood bleached kraft pulp (NBKP).

[0015] The paper substrate layer may also have a pigment coating layer. The pigment coating layer may be one layer or two or more layers. The pigment coating layer preferably contains a pigment and a binder. Examples of pigments include, but are not limited to, heavy calcium carbonate, kaolin, and plastic pigments. Examples of binders include, but are not limited to, starch, styrene-acrylic copolymer latex, styrene-butadiene copolymer latex, and olefin-carboxylic acid emulsion copolymer latex.

[0016] The thickness of the paper base layer in the waste paper pieces is preferably 100 μm or more and 600 μm or less, more preferably 120 μm or more and 550 μm or less, even more preferably 150 μm or more and 500 μm or less, and even more preferably 200 μm or more and 450 μm or less, from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. When a piece of waste paper has a plurality of paper base layers, the thickness of the paper base layer in the piece of waste paper indicates the total thickness of the respective paper base layers.

[0017] The basis weight of the paper base layer in the waste paper pieces is preferably 80 g / m from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. 2 More than 400g / m 2 or less, more preferably 100 g / m 2 More than 350g / m 2 More preferably, 120 g / m or less 2 More than 300g / m 2 or less, even more preferably 150 g / m 2More than 250g / m 2 The following is the result. When a waste paper piece has a plurality of paper base layers, the basis weight of the paper base layers in the waste paper piece indicates the total basis weight of the respective paper base layers.

[0018] In this embodiment, the waste paper pieces may have other layers in addition to the resin layer and paper substrate layer, such as a metal layer, a printed layer, and an adhesive layer.

[0019] [Metal layer] In this embodiment, the waste paper pieces may further have a metal layer. In this embodiment, the metal layer of the waste paper pieces preferably contains aluminum. Furthermore, in this embodiment, the metal layer of the waste paper pieces is more preferably aluminum foil. When the waste paper pieces contain a metal layer, the thickness of the metal layer in the waste paper pieces is preferably 1 μm or more and 50 μm or less, more preferably 3 μm or more and 40 μm or less, even more preferably 5 μm or more and 30 μm or less, and even more preferably 6 μm or more and 20 μm or less. In addition, when a piece of waste paper has a plurality of metal layers, the thickness of the metal layers on the piece of waste paper indicates the total thickness of the respective metal layers. When the thickness of the metal layer is 1 μm or more, the metal layer is prevented from becoming too fine when the resulting bale is disintegrated, making the disintegration process more efficient. Also, when the thickness of the metal layer is 50 μm or less, the penetration of moisture into the waste paper pieces is less likely to be hindered, making the disintegration process more efficient.

[0020] When the waste paper pieces contain a metal layer, the basis weight of the metal layer in the waste paper pieces is preferably 8 g / m from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. 2 More than 30g / m 2 Less than 10 g / m, more preferably 2 More than 27g / m 2 or less, more preferably 12 g / m 2 More than 24g / m 2 or less, even more preferably 14 g / m 2 More than 22g / m 2 The following is the result. When a piece of waste paper has a plurality of metal layers, the basis weight of the metal layers in the piece of waste paper indicates the total basis weight of the respective metal layers.

[0021] [Printing layer] In this embodiment, the waste paper pieces may have a printed layer. An example of the printed layer is a printed layer provided on a paper substrate layer. The printed layer may be formed using a known ink such as an oil-based ink, a water-based ink, or a biomass ink. The printed content may be a pattern, a design, or information (ingredients, expiration date, QR Code (registered trademark), etc.). The printed layer may be formed on the entire surface or on a part of the layer to which the printed layer is applied.

[0022] In this embodiment, the folding strength of the waste paper pieces is preferably 20 gf or more and 350 gf or less, more preferably 25 gf or more and 300 gf or less, even more preferably 30 gf or more and 200 gf or less, even more preferably 35 gf or more and 100 gf or less, and even more preferably 40 gf or more and 70 gf or less. Although there is no particular lower limit to the bending strength, from the viewpoint of manufacturing, the lower limit is preferably 20 gf or more. Furthermore, by keeping the bending strength at 350 gf or less, the force that causes the waste paper pieces to return to their original shape is suppressed, thereby further improving the shape retention of the bale. In this embodiment, the folding strength of the waste paper pieces can be adjusted to a desired range by adjusting the amount of paper strength agent added to the paper base layer of the waste paper pieces, the basis weight of the waste paper pieces, and the thickness of the waste paper pieces. The folding strength of the waste paper pieces is measured by the method described in the Examples.

[0023] [Adhesive layer] In this embodiment, the waste paper pieces may further have an adhesive layer, which is formed mainly to adhere the metal layer to the paper base layer when the waste paper has a metal layer, and / or to adhere the metal layer to the resin layer. Examples of resins that may be used to form the adhesive layer include ethylene-methacrylic acid copolymer resin (EMAA), ethylene-acrylic acid copolymer resin (EAA), ethylene-vinyl acetate copolymer resin (EVA), ionomer resin (IO), ethylene-methyl acrylate copolymer resin (EMA), ethylene-ethyl acrylate copolymer resin (EEA), and ethylene-butyl acrylate copolymer resin (EBA).

[0024] In this embodiment, the median area of ​​the waste paper pieces is preferably 20 cm 2 More than 200cm 2 Less than 30cm, preferably 2 over 180cm 2 Less than 40cm, more preferably 2 More than 150cm 2 Less than or equal to 50cm, even more preferably 2 More than 120cm 2 Less than 60cm, more preferably 2 More than 90cm 2 The following is the result. The median area of ​​the waste paper pieces is 20 cm 2 By setting the median area of ​​the waste paper pieces at 200 cm or more, the shape retention of the resulting bale is further improved. 2 When the temperature is equal to or less than this, the disintegration property is further improved. The median area of ​​the waste paper pieces is measured by the method described in the Examples.

[0025] In this embodiment, the content of sizing agent in the paper base layer of the waste paper pieces is preferably 0.2% by mass or more and 2.1% by mass or less, more preferably 0.4% by mass or more and 1.8% by mass or less, and even more preferably 0.6% by mass or more and 1.6% by mass or less, from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. The content of sizing agent in the paper base layer of the waste paper pieces does not change before and after bale formation. That is, the content of sizing agent in the paper base layer of the waste paper pieces is the same as the content of sizing agent in the paper base layer of the waste paper pieces contained in the resulting bale. The content of sizing agent in the paper base layer of the waste paper pieces is measured by the method described in the Examples.

[0026] In this embodiment, examples of the sizing agent in the paper base layer of the waste paper pieces include rosin sizing agents, synthetic sizing agents, and petroleum resin-based sizing agents.

[0027] In this embodiment, the amount of paper strength agent added to the waste paper pieces relative to 100 parts by mass of raw pulp in the pulp slurry when producing the paper base layer is preferably 0.5 to 1.5 parts by mass, more preferably 0.7 to 1.3 parts by mass, and even more preferably 0.9 to 1.1 parts by mass, from the viewpoint of improving the shape retention and disintegration properties of the resulting bale. Furthermore, the content of the paper strength agent in the paper base layer is preferably 0.5 to 1.5% by mass, more preferably 0.7 to 1.3% by mass, and even more preferably 0.9 to 1.1% by mass. The content of the paper strength agent in the paper base layer of the waste paper pieces does not change before and after bale formation, i.e., the content of the paper strength agent in the paper base layer of the waste paper pieces is the same as the content of the paper strength agent in the paper base layer of the waste paper pieces contained in the resulting bale.

[0028] In this embodiment, the paper strength agents in the paper base layer of the waste paper pieces include dry strength agents and wet strength agents. Examples of dry strength agents include polyacrylamide, cationized starch, and carboxymethyl cellulose. Examples of wet strength agents include polyamide polyamine epichlorohydrin, urea formaldehyde resin, and melamine formaldehyde resin.

[0029] Examples of the waste paper pieces include waste paper pieces derived from food and beverage containers, paper bags, and paper cutlery. Examples of food and beverage containers include liquid containers and food containers, and more specifically, paper trays, aseptic containers, paper cups, milk cartons, etc. Among these, the waste paper pieces are preferably one or more types selected from waste paper pieces from aseptic containers and waste paper pieces from paper cups. The waste paper pieces for aseptic containers have, for example, the following structures (a1) to (a2). In the structures below, the layer on the right indicates the layer that was in contact with the contents when used as an aseptic container. In the structures below, the "(printed layer)" and "(adhesive layer)" are optional layers that may or may not be present as necessary. In the structures below, the paper substrate layer may have the above-mentioned pigment coating layer, and a printed layer may be provided on the pigment coating layer. In the structures below, the "resin layer" may be one layer or two or more layers. (a1): Resin layer / (printing layer) / paper base layer / resin layer / metal layer / (adhesive layer) / resin layer (a2): Resin layer / (printing layer) / paper base layer / resin layer / resin layer (barrier layer) / (adhesive layer) / resin layer

[0030] The recycled paper pieces for paper cups preferably have the following structures (b1) to (b4), for example. In the structures below, the layer on the right indicates the layer that was in contact with the contents when used as a paper cup. In the structures below, the "(printed layer)" and "(adhesive layer)" are optional layers that may or may not be present as necessary. In the structures below, the paper base layer may have the above-mentioned pigment coating layer, and a printed layer may be provided on the pigment coating layer. In the structures below, the "resin layer" may be one layer or two or more layers. (b1): (printing layer) / paper base layer / resin layer / (adhesive layer) / metal layer / (adhesive layer) / resin layer (b2): (printing layer) / paper base layer / resin layer / (adhesive layer) / resin layer (b3): ​​Resin layer / (Printing layer) / Paper base layer / Resin layer (b4): (printing layer) / resin layer / paper base layer / resin layer

[0031] (molding process) This embodiment includes a molding step in which waste paper pieces having at least a resin layer and a paper base layer are compressed and molded to obtain a bale. As the bale molding device in the molding step, a known bale molding device may be used as appropriate.

[0032] In the forming step, the bale forming pressure is preferably 500 kN / m 2 More than 2500N / m 2 Less than or equal to 1000 kN / m 2 More than 2300N / m 2 or less, more preferably 1200 kN / m 2 More than 2000N / m 2 The following is the result. By keeping the bale molding pressure within the above range, the density of the resulting bale falls within the desired bale density range described below, and the shape retention and disintegration properties of the resulting bale are further improved.

[0033] (Crushing process) In this embodiment, it is preferable to include a crushing step in which waste paper is crushed before bale formation. That is, the bale manufacturing method of this embodiment preferably includes a crushing step in which waste paper is crushed before the above-mentioned forming step. By including the crushing step, the waste paper pieces to be subjected to the forming step are made uniform in size, so that when the resulting bale is subjected to recycling, for example, by recovering pulp fibers from the bale, the defibration process becomes more efficient and the defibration properties are further improved. In addition, the shape retention of the resulting bale is further improved. As the crusher used in the crushing step, it is preferable to use a single-shaft crusher, a twin-shaft crusher, etc., depending on the size of the waste paper pieces after crushing. Furthermore, when the crushing step is carried out, if the washing step described below is carried out at the same time, it is preferable to use a crushing and washing machine, etc. In this embodiment, if a shredding process is not performed, unshredded waste paper may be used as waste paper pieces as is.

[0034] In the shredding step, the number of hooks of the shredding machine is preferably 2 or more and 10 or less, more preferably 4 or more and 8 or less, from the viewpoint of keeping the median area of ​​the waste paper pieces within a desired range.

[0035] (Cleaning process) This embodiment preferably includes a washing step of washing the waste paper or waste paper pieces before bale formation. That is, the bale manufacturing method of this embodiment preferably includes a washing step of washing the waste paper or waste paper pieces before the above-mentioned forming step. Furthermore, if the bale manufacturing method of this embodiment includes a crushing step before the washing step, the washing step is preferably a step of washing the waste paper pieces after the crushing step. In the washing step, water is usually used as the washing water for washing the waste paper pieces. The washing step may be carried out before the crushing step, after the crushing step and before the molding step, or simultaneously with the crushing step. Among these, from the viewpoint of washing efficiency, it is preferable to carry out the washing step after the crushing step and before the molding step, or to carry out the crushing step and the washing step simultaneously, and it is more preferable to carry out the crushing step and the washing step simultaneously. Any known device can be used in the washing step. When the crushing step and the washing step are carried out simultaneously, it is preferable to use a crushing / washing machine or the like.

[0036] [Veil] In this embodiment, the bale can be obtained by the above-described bale manufacturing method, and therefore the bale in this embodiment has excellent shape retention and excellent disintegration properties for the waste paper pieces contained in the bale.

[0037] In this embodiment, the density of the bale is preferably 0.3 t / m 3 More than 1.0t / m 3 Less than 0.4t / m, preferably 0.4t / m 3 More than 0.8t / m 3 or less, more preferably 0.5 t / m 3 More than 0.7t / m 3 The following is the result. Bale density is 0.3t / m 3 By setting the density of the bale to 1.0 t / m or more, the waste paper pieces are in close contact with each other within the bale, and the shape retention is further improved. 3By keeping the thickness below 1 / 2 mm, it is possible to prevent the waste paper pieces from being compressed more tightly than necessary within the bale, which makes it easier to loosen the bale when it is recycled, improving the disintegration properties.

[0038] In this embodiment, the bale obtained is made from the above waste paper pieces. Furthermore, the structure and other physical properties of the above waste paper pieces do not change before and after bale formation. In other words, in this embodiment, the form of the waste paper pieces contained in the bale is the same as the waste paper pieces exemplified in the above bale manufacturing method. In this embodiment, the resulting bale may contain waste paper other than the waste paper pieces described above, as long as the effects of the present invention are not impaired. Furthermore, in this embodiment, the resulting bale may contain foreign matter other than the waste paper pieces described above, as long as the effects of the present invention are not impaired. Examples of foreign matter include straws, caps for food and beverage containers, and lids for food and beverage containers. In this embodiment, the content of the waste paper pieces in the resulting bale is preferably 90% by mass or more, more preferably 95% by mass or more, and even more preferably 100% by mass. [Example]

[0039] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below. In the examples and comparative examples, "parts" and "%" refer to "parts by mass" and "% by mass," respectively, unless otherwise specified. Furthermore, the operations in the examples and comparative examples were carried out under conditions of 23±1°C and 50±2% RH, unless otherwise specified.

[0040] [Bale manufacturing method] Example 1 (pieces of waste paper) The waste paper pieces used were those of composition 1 in Table 1. The paper base layer of the waste paper pieces in Example 1 was obtained from a paper stock (pulp slurry) to which 100 parts by mass of raw pulp (pulp composition (mass ratio): softwood bleached kraft pulp (NBKP) / hardwood bleached kraft pulp (LBKP) = 40 / 60, redisintegrated freeness (CSF): 550 mL) was added, 1.0 part by mass of a rosin sizing agent (Sizepine N-881, manufactured by Arakawa Chemical Industries, Ltd.), 1.0 part by mass of a polyacrylamide-based paper strength agent (PS117, manufactured by Arakawa Chemical Industries, Ltd.), and 1.0 part by mass of aluminum sulfate were added. (Crushing process / washing process) The waste paper pieces were placed in a shredding and washing machine (Paper Container Recycling Machine PPRS, manufactured by A-tech Corporation), shredded with blades having six hooks, and washed with water. (Bale forming process) Approximately 60 kg of waste paper pieces were fed into a bale compressor (Yuken Kogyo Co., Ltd., YB-32M-PA-10, bale size: 640 x 430 x 350 mm) and the bale was formed under a pressure of 1800 kN / m 2 The mixture was compressed at a bale forming pressure of 1000 kJ / g to obtain a bale.

[0041] <Example 2> The waste paper pieces used were those of composition 2 in Table 1, and the bale forming pressure in the bale forming process was 1700 kN / m 2 A veil was obtained in the same manner as in Example 1, except that: The paper base layer of the waste paper pieces in Example 2 was obtained from a paper stock (pulp slurry) to which 100 parts by mass of raw pulp (pulp composition (mass ratio): softwood bleached kraft pulp (NBKP) / hardwood bleached kraft pulp (LBKP) = 40 / 60, redisintegrated freeness (CSF): 440 mL) was added, 1.5 parts by mass of a rosin sizing agent (Sizepine N-881, manufactured by Arakawa Chemical Industries, Ltd.), 1.0 part by mass of a polyacrylamide-based paper strength agent (PS117, manufactured by Arakawa Chemical Industries, Ltd.), and 1.0 part by mass of aluminum sulfate were added.

[0042] Example 3 Bales were obtained in the same manner as in Example 1, except that waste paper pieces of Configuration 1 were used, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 0.5 parts by mass per 100 parts by mass of raw pulp.

[0043] Example 4 Bales were obtained in the same manner as in Example 1, except that waste paper pieces of Configuration 1 were used, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 0.8 parts by mass per 100 parts by mass of raw pulp.

[0044] <Example 5> Bales were obtained in the same manner as in Example 1, except that waste paper pieces of Configuration 1 were used, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 1.2 parts by mass per 100 parts by mass of raw pulp.

[0045] Example 6 Bales were obtained in the same manner as in Example 1, except that waste paper pieces of Configuration 1 were used, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 1.5 parts by mass per 100 parts by mass of raw pulp.

[0046] Example 7 The waste paper pieces used were those of Configuration 1, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 1.1 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1850 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0047] Example 8 The waste paper pieces used were those of Configuration 1, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 1.2 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1900 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0048] Example 9 The waste paper pieces used were those of Configuration 1, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 0.9 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1700 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0049] Example 10 The waste paper pieces used were those of Configuration 1, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 0.8 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1650 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0050] Example 11 Bales were obtained in the same manner as in Example 2, except that waste paper pieces of Configuration 2, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 1.2 parts by mass per 100 parts by mass of raw pulp, were used.

[0051] Example 12 Bales were obtained in the same manner as in Example 2, except that waste paper pieces of Configuration 2, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 1.4 parts by mass per 100 parts by mass of raw pulp, were used.

[0052] Example 13 Bales were obtained in the same manner as in Example 2, except that waste paper pieces of Configuration 2, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 1.8 parts by mass per 100 parts by mass of raw pulp, were used.

[0053] Example 14 Bales were obtained in the same manner as in Example 2, except that waste paper pieces of Configuration 2, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 2.0 parts by mass per 100 parts by mass of raw pulp, were used.

[0054] Example 15 The waste paper pieces used were those of Configuration 2, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 1.1 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1800 kN / m 2 A veil was obtained in the same manner as in Example 2, except that:

[0055] Example 16 The waste paper pieces used were those of Configuration 2, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 1.2 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1850 kN / m 2 A veil was obtained in the same manner as in Example 2, except that:

[0056] Example 17 The waste paper pieces used were those of Configuration 2, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 0.9 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1650 kN / m 2 A veil was obtained in the same manner as in Example 2, except that:

[0057] Example 18 The waste paper pieces used were those of Configuration 2, in which the amount of paper strength agent added to the paper material (pulp slurry) when manufacturing the paper base layer was 0.8 parts by mass per 100 parts by mass of raw pulp, and the bale forming pressure in the bale forming process was 1600 kN / m 2 A veil was obtained in the same manner as in Example 2, except that:

[0058] Example 19 The number of blade hooks in the crushing process was set to 3, and the bale forming pressure in the bale forming process was set to 1900 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0059] Example 20 The number of blade hooks in the crushing process was set to 9, and the bale forming pressure in the bale forming process was set to 1700 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0060] Example 21 The bale forming pressure during the bale forming process is 1400kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0061] Example 22 The bale forming pressure during the bale forming process is 2200kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0062] Example 23 The crushing and washing processes were not carried out, and the bale forming pressure in the bale forming process was set to 2200 kN / m 2 A veil was obtained in the same manner as in Example 1, except that:

[0063] Example 24 The crushing and washing processes were not carried out, and the bale forming pressure in the bale forming process was set to 2000 kN / m 2 A veil was obtained in the same manner as in Example 2, except that:

[0064] <Comparative Example 1> Bales were obtained in the same manner as in Example 1, except that waste paper pieces of Configuration 1 were used, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 0.1 parts by mass per 100 parts by mass of raw pulp.

[0065] <Comparative Example 2> Bales were obtained in the same manner as in Example 2, except that waste paper pieces of Configuration 2, in which the amount of sizing agent added to the paper stock (pulp slurry) when producing the paper base layer was 2.2 parts by mass per 100 parts by mass of raw pulp, were used.

[0066] The composition of the waste paper pieces used in the examples and comparative examples is shown in Table 1.

[0067] [Table 1]

[0068] [Evaluation and measurement methods] <Water absorption over 24 hours> The waste paper pieces used in the examples and comparative examples were completely dried and then conditioned for 96 hours in a humidity-controlled environment specified in JIS P 8111:1998. Approximately 10 g of the conditioned waste paper pieces were immersed in 1 L of water (water temperature: 23±1°C) for 24 hours, and then the waste paper pieces were collected. The collected waste paper pieces were sandwiched between absorbent paper (Advantec, No. 26, 190 mm x 190 mm) and rolled back and forth once with a metal roller (10 kg) without applying pressure to remove excess moisture. This was used as the waste paper piece after immersion in water. The mass of the waste paper piece before and after immersion in water was measured (measured to the nearest 1 mg), and the water absorbency was calculated using the following formula. This was used as the 24-hour water absorbency of the waste paper piece. [Water absorption (%)] = ([Mass of waste paper piece after immersion in water (g)] - [Mass of waste paper piece before immersion in water (g)]) / [Mass of waste paper piece before immersion in water (g)] × 100

[0069] <Bending strength> The waste paper pieces used in the examples and comparative examples were dried completely and then conditioned for 96 hours in a humidity-controlled environment as specified in JIS P 8111: 1998. Waste paper samples (width 38 mm x length 70 mm) were prepared from the conditioned waste paper pieces, and the bending strength of the waste paper samples was measured using a bending stiffness tester (BST-150M, manufactured by Asahi Research Institute).

[0070] <Median area of ​​waste paper pieces> Approximately 100 g of the waste paper pieces used in the examples and comparative examples were passed through a sieve (φ: 20 mm) to remove small waste paper pieces, and the remaining waste paper pieces were scanned using an Epson Scan to obtain images. The scanned images were analyzed using ImageJ, and the area of ​​each waste paper piece was obtained to calculate the median area.

[0071] <Sizing agent content> Pieces of waste paper were randomly collected from the bales obtained in the Examples and Comparative Examples and then dried. After drying, layers other than the paper base layer, such as the resin layer, were removed by grinding using a grinding device (manufactured by Sagawa Corporation, grinding wheel dimensions φ50.8 × 12.7 mm) while checking the layer boundaries under a microscope, and the paper base layer was recovered. The additives in the recovered paper base layer were quantified using pyrolysis gas chromatography (GCMS) under the following measurement conditions: Quantification was performed based on a calibration curve prepared using a rosin sizing agent (Sizepine N-881, manufactured by Arakawa Chemical Industries, Ltd.) of known concentration as a standard. (Measurement conditions) ·Pyrolysis furnace temperature: 450℃ Measurement temperature conditions: 100 to 325°C, temperature increased at 15°C / min Column used: HP-5MS (Agilent Technologies)

[0072] <Bale density> The bale density was calculated from the weight of the waste paper pieces added during the bale forming process and the volume of the resulting bale.

[0073] <Shape retention> Five PP bands (manufactured by Moriya Sangyo Co., Ltd., model number: 12 J-S1) were wrapped evenly around the sides of the bales obtained in the examples and comparative examples using a cordless handheld packaging machine (manufactured by Strapak Co., Ltd., STB73, tightening strength 900N), and then stretch film (manufactured by Trusco Nakayama Co., Ltd., SF18-500) was wrapped around them so that the entire side of the bale was covered. The forklift tines were inserted directly between the bale and the ground, lifted vertically 1m, and then lowered to the ground. When the forklift tines were then pulled out from between the bale and the ground, the state of the bale falling out was checked and evaluated according to the following criteria. (Evaluation criteria) A: Pieces of waste paper had spread out and fallen off the bale to a distance of less than 15 cm. B: Pieces of waste paper had fallen off from the bale to a distance of 15 cm or more but less than 30 cm. C: Pieces of waste paper had fallen off from the bale, extending over a distance of 30 cm to less than 45 cm. D: Pieces of waste paper had spread out from the bale to a distance of more than 45 cm and had fallen off.

[0074] <Disintegrability> From the bales obtained in the Examples and Comparative Examples, 60 g of waste paper pieces (on an absolute dry basis) were collected and disintegrated for 15 minutes using a disintegrator (Kumagaya Riki Kogyo Co., Ltd., No. 2532) to obtain a pulp slurry with a solid concentration of 3% by mass. The resulting pulp slurry was then fed into a flat screen (Kumagaya Riki Kogyo Co., Ltd., No. 230703, 6-cut slit) at a flow rate of 10 L / min for 15 minutes. The residue rate was calculated from the absolute dry weight of the residue that did not pass through the flat screen, and the fiber recovery rate was calculated using the following formula, which was used as an index of disintegration ability. Fiber recovery rate (%) = {1 - ([residue rate (%)] / 100)} / Proportion of the basis weight of the paper base layer in the basis weight of the waste paper piece × 100 Residue rate (%) = [bone dry mass (g) of residue that did not pass through the flat screen] / [mass (g) of solids in the pulp slurry introduced into the flat screen] × 100 (Evaluation results) A: Fiber recovery rate is 90% or more B: Fiber recovery rate is 70% or more but less than 90% C: Fiber recovery rate is 50% or more but less than 70% D: Fiber recovery rate is less than 50%

[0075] Table 2 shows the measurement and evaluation results for the examples and comparative examples.

[0076] [Table 2]

[0077] From Table 2, it was confirmed that the bales obtained in Examples 1 to 24 had excellent shape retention and also excellent disintegration properties because the 24-hour water absorption of the waste paper pieces was 15% or more and 85% or less. On the other hand, the bale obtained in Comparative Example 1 had poor shape retention because the 24-hour water absorption of the waste paper pieces was greater than 85%. Also, the bale obtained in Comparative Example 2 had poor disintegration properties because the 24-hour water absorption of the waste paper pieces was less than 10%. [Industrial Applicability]

[0078] The bale manufacturing method of the present invention has the above-mentioned characteristics, and therefore the formed bale has excellent shape retention and also has excellent disintegration properties.

Claims

1. The method includes a molding step of compressing and molding waste paper pieces having at least a resin layer and a paper base layer to obtain a bale, The basis weight of the waste paper pieces is 100 g / m ２ That's all, The water absorption rate of the waste paper pieces in 24 hours is 15% or more and 85% or less. How the veil is made.

2. The method for manufacturing a bale according to claim 1, wherein the folding strength of the waste paper pieces is 20 gf or more and 350 gf or less.

3. The median area of ​​the waste paper pieces is 20 cm ２ More than 200cm ２ The method for producing a bale according to claim 1 or 2, wherein:

4. Bale density is 0.3t / m ３ 1.0t / m or more ３ The method for producing a bale according to claim 1 or 2, wherein:

5. The method for manufacturing a bale according to claim 1 or 2, wherein the content of the sizing agent in the paper base layer of the waste paper pieces is 0.2% by mass or more and 2.1% by mass or less.

6. The method for manufacturing a bale according to claim 1 or 2, wherein the waste paper pieces further have a metal layer.

7. Bale forming pressure: 500 kN / m ２ More than 2500kN / m ２ The method for producing a bale according to claim 1 or 2, wherein:

8. The method for producing a bale according to claim 1 or 2, further comprising a crushing step of crushing the waste paper before forming the bale.

9. 3. The method for producing a bale according to claim 1, further comprising a washing step of washing the waste paper or waste paper pieces before forming the bale.

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