Paper drain

Abstract

To provide a novel paper drain.SOLUTION: A paper drain has one or more paper substrates, and has a wet tensile strength of 2.0 kN / m or more and a water absorption per unit area (TWA) of 300 g / m2 or more. The paper drain has two or more paper substrates bonded together. The paper drain has a paper substrate with a Cobb water absorption (120 seconds) of 300 g / m2 or less. The paper drain has a first paper substrate with a Cobb water absorption (120 seconds) of 300 g / m2 or less and a second paper substrate with a water absorption per unit area (TWA) of 300 g / m2 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a paper drain used to improve soft ground. [Background technology]

[0002] Accelerated consolidation is one of the methods for improving soft ground. Accelerated consolidation involves placing drainage material in the soft ground to be improved, and then applying loads of construction soil or other earth on top of it to generate excess pore water pressure. This excess pore water pressure causes excess water to move along the drain, which is then finally discharged to the outside for drainage. This accelerates the consolidation of the soft ground, increasing its strength. Drainage materials are generally made of plastic or metal. However, used drainage materials are usually left in the soil even after ground improvement. For this reason, methods have been proposed that use biodegradable plastics (Patent Document 1) and that accelerate the decomposition of biodegradable plastics using alkaline substances after ground improvement (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-100443 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-266340 Summary of the Invention [Problem to be solved by the invention]

[0004] The objective is to provide a new paper drain. [Means for solving the problem]

[0005] The means for solving the problems of the present invention are as follows. 1.Having one or more sheets of paper substrate, Wet tensile strength of 2.0 kN / m or more, water absorption per unit area (TWA) of 300 g / m 2 A paper drain characterized by the above. 2. The paper drain described in 1., characterized in that two or more sheets of paper substrate are bonded together. 3. COBB absorbency (120 seconds) is 300g / m 2 The paper drain according to 1. or 2., characterized in that it has a paper base material as follows: 4. COBB absorbency (120 seconds) is 300g / m 2 a first paper substrate, which is Water absorption per unit area (TWA) is 300g / m 2 The second paper substrate as described above, 2. The paper drain according to claim 2, characterized in that [Effects of the Invention]

[0006] The paper drain of the present invention has excellent durability and drainage properties and can be used practically as a drain material for improving soft ground. Because the paper drain of the present invention is biodegradable, it will not decompose over time and will not remain in the soil even if left as is after use. DETAILED DESCRIPTION OF THE INVENTION

[0007] The paper drain of the present invention has one or more paper substrates, a wet tensile strength of 2.0 kN / m or more, and a water absorption per unit area (TWA) of 300 g / m. 2 That's all. The paper drain of the present invention may be one that drains water either vertically or horizontally. Paper drain A paper drain may have one or more paper substrates, and may be a single paper substrate or a laminate of two or more paper substrates. However, a laminate of two or more paper substrates is preferred because it increases the overall water absorption capacity while maintaining high wet tensile strength, i.e., it is easier to achieve both durability and drainage. There is no particular limit to the number of paper substrates to be laminated, and it can be designed depending on the weight (basis weight) and water absorption capacity of the paper drain, but two or three sheets are preferred from the viewpoint of simplifying the manufacturing process. When two or more paper substrates are laminated, the paper substrates may be the same or different.

[0008] The paper drain of the present invention has a wet tensile strength of 2.0 kN / m or more. Because the paper drain of the present invention has a wet tensile strength of 2.0 kN / m or more, it is less likely to break even when force is applied during installation or use, has excellent durability, and can maintain drainage performance over a period of use. The wet tensile strength of the paper drain of the present invention is preferably 3.0 kN / m or more, more preferably 4.0 kN / m or more, even more preferably 5.0 kN / m or more, even more preferably 6.0 kN / m or more, even more preferably 7.0 kN / m or more, even more preferably 8.0 kN / m or more, even more preferably 9.0 kN / m or more, and even more preferably 10.0 kN / m or more.

[0009] The paper drain of the present invention has a water absorption per unit area (TWA) of 300 g / m 2 The paper drain of the present invention has a TWA of 300 g / m 2 The TWA of the paper drain of the present invention is 350 g / m. 2 More than 400g / m 2 More preferably, 450 g / m 2 More preferably, 500 g / m 2 More preferably, 550 g / m 2 More preferably, 600 g / m 2 More preferably, 650 g / m 2 More preferably, 700 g / m 2The above is even more preferable.

[0010] The paper drain of the present invention has a COBB absorbency (120 seconds) of 300 g / m 2 The paper drain of the present invention is intended to be left in the soil for a long period of time to drain water, and it is preferable that the COBB water absorbency (120 seconds) is 300 g / m or less. 2 The paper drain has excellent water resistance and can maintain its shape even during use. The COBB water absorbency (120 seconds) is 250 g / m 2 Less than 200 g / m is more preferable. 2 More preferably, 150 g / m 2 Even more preferably, 100 g / m 2 The lower limit of the Cobb water absorbency (120 seconds) is not particularly limited, but for example, it is 1 g / m 2 More than 2g / m 2 More than 3g / m 2 The above may be the case.

[0011] The weight (basis weight) of the paper drain of the present invention is not particularly limited as long as it satisfies the above-mentioned wet tensile strength and TWA. For example, 2 It is preferable that the weight of the paper drain is 500g / m or more, because it is easy to increase the TWA. 2 More than 700g / m 2 More than 900g / m 2 The upper limit of the weight of the paper drain is not particularly limited, but for example, 2000 g / m 2 Below 1800g / m 2 Below 1600g / m 2 It can be as follows:

[0012] The thickness of the paper drain of the present invention is not particularly limited as long as it satisfies the above-mentioned wet tensile strength and TWA, but is preferably 300 μm or more, for example, because this makes it easier to increase the wet tensile strength. The thickness of the paper drain is more preferably 500 μm or more, even more preferably 700 μm or more, and even more preferably 900 μm or more. The upper limit of the thickness of the paper drain is not particularly limited, but can be, for example, 2000 μm or less, 1800 μm or less, 1600 μm or less, etc.

[0013] The density of the paper drain of the present invention is not particularly limited as long as it satisfies the above-mentioned wet tensile strength and TWA. For example, it is 0.9 g / cm 3 It is preferable that the density of the paper drain is 0.85 g / cm or less, because this makes it easier to increase the TWA. 3 Less than 0.8 g / cm is more preferable. 3 More preferably, 0.75 g / cm 3 The lower limit of the density of the paper drain is not particularly limited, but for example, it is 0.45 g / cm 3 , 0.5g / cm 3 , 0.55g / cm 3 etc.

[0014] ·Paper base material In the present invention, the paper substrate may be either a paper consisting of only a single paper layer or a multi-layer paper having two or more paper layers. When the paper substrate is a multi-layer paper, it is composed of a surface layer, an optional middle layer, and a back layer, with the surface layer and back layer being the outermost layers. The number of layers of the multi-layer paper can be set according to the required basis weight, etc. The pulp contained in the paper base material is not particularly limited, and may be one or a mixture of two or more types of pulp derived from wood fibers, such as unbleached hardwood kraft pulp (LUKP), unbleached softwood kraft pulp (NUKP), bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), recycled paper pulp, groundwood pulp (GP), refiner ground pulp (RGP), chemical pulp (CP), thermomechanical pulp (TMP), and chemithermomechanical pulp (CTMP), as well as non-wood pulps obtained from kenaf, bagasse, bamboo, hemp, straw, etc. Among these, kraft pulp is preferred from the viewpoint of wet tensile strength, and hardwood kraft pulp, which has excellent water retention, is more preferred. Furthermore, recycled paper pulp is preferred from the viewpoint of cost.

[0015] The Canadian Standard Freeness of the pulp used in the present invention is not particularly limited as long as a paper drain satisfying the above-mentioned wet tensile strength and TWA can be obtained, but since it is easy to increase the TWA value, it is preferably 300 ml CSF or more, more preferably 400 ml CSF or more, even more preferably 500 ml CSF or more, and even more preferably 600 ml CSF or more. When the paper base material is a multi-layer paper, the pulp compositions and Canadian Standard Freenesses of the respective paper layers may be the same or different. The paper base material may contain known internal additives such as retention aids, bulking agents, dry strength improvers, wet strength improvers, drainage improvers, water retention agents, dyes, sizing agents, etc., but the inclusion of wet strength improvers and internal sizing agents is preferred because they help maintain the shape better during use. When the paper base material is a multi-layer paper, the type and content of the internal additives may be different for each paper layer, or may be the same.

[0016] If necessary, known fillers can be added to the paper substrate. Examples of fillers include inorganic fillers such as kaolin, calcined kaolin, delaminated kaolin, clay, calcined clay, delaminated clay, illite, heavy calcium carbonate, light calcium carbonate, light calcium carbonate-silica composite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, as well as organic fillers such as urea-formalin resin, polystyrene resin, and phenolic resin. One or more types of fillers can be used. When the paper substrate is a multi-layer paper, the type and content of the filler in each paper layer can be the same or different.

[0017] The surface of the paper substrate can be treated with various chemicals as needed. Examples of chemicals that can be used include oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, polyacrylamide, polyvinyl alcohol, surface sizing agents, water-resistant agents, water-retention agents, thickeners, and lubricants. Treatment with a surface sizing agent is preferred because it helps the paper maintain its shape better during use. Furthermore, these chemicals can be used in combination with pigments. Examples of pigments include inorganic pigments such as kaolin, clay, engineered kaolin, delaminated clay, heavy calcium carbonate, light calcium carbonate, mica, talc, titanium dioxide, barium sulfate, calcium sulfate, zinc oxide, silicic acid, silicates, colloidal silica, and satin white, as well as solid, hollow, or core-shell organic pigments, which can be used alone or in combination of two or more.

[0018] The basis weight of the paper substrate is not particularly limited, but is, for example, 50 g / m 2 More than 800g / m 2 In the case of multi-layer paper, the basis weight of each paper layer is 10 g / m 2 More than 250g / m 2 It can be as follows:

[0019] The paper drain of the present invention has a COBB absorbency (120 seconds) of 300 g / m2 It is preferred to have a paper substrate that is: The COBB water absorption (120 seconds) of the paper substrate is 250 g / m 2 Less than 200 g / m is more preferable. 2 More preferably, 150 g / m 2 Even more preferably, 100 g / m 2 The lower limit of the COBB water absorbency (120 seconds) of this paper substrate is not particularly limited, but for example, it is 1 g / m 2 More than 2g / m 2 More than 3g / m 2 The above may be the case.

[0020] When the paper drain of the present invention is made of two or more paper substrates bonded together, the COBB water absorption (120 seconds) is 300 g / m 2 a first paper substrate having a water absorption per unit area (TWA) of 300 g / m or less; 2 It is preferable to have a second paper substrate that satisfies the above requirements. A paper drain that satisfies this requirement can achieve high levels of both durability and drainage. The arrangement of the first and second paper substrates is not particularly limited; for example, when three or more paper substrates are bonded together, the first and second paper substrates may be located on the outermost surface that comes into contact with the soil, or they may be located inside the paper substrates located on the outermost surfaces.

[0021] The COBB water absorption (120 seconds) of the first paper substrate is 250 g / m 2 Less than 200 g / m is more preferable. 2 More preferably, 150 g / m 2 Even more preferably, 100 g / m 2 The lower limit of the COBB water absorbency (120 seconds) of this paper substrate is not particularly limited, but for example, it is 1 g / m 2 More than 2g / m 2 More than 3g / m 2 The above may be the case. The TWA of the second paper substrate is 350 g / m 2 More than 400g / m 2 More preferably, 450 g / m 2is more preferable, and 500 g / m 2 More preferably, 550 g / m 2 More preferably, 600 g / m 2 More preferably, 650 g / m 2 More preferably, 700 g / m 2 The above is even more preferable.

[0022] ·glue The paper drain of the present invention is preferably formed by bonding two or more paper substrates together. The adhesive for laminating the paper substrate is not particularly limited, and any adhesive known in the papermaking field can be used without limitation. For example, polyvinyl alcohols such as fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, diacetone-modified polyvinyl alcohol, acetoacetyl-modified polyvinyl alcohol, amide-modified polyvinyl alcohol, sulfonic acid-modified polyvinyl alcohol, butyral-modified polyvinyl alcohol, olefin-modified polyvinyl alcohol, nitrile-modified polyvinyl alcohol, pyrrolidone-modified polyvinyl alcohol, silanol-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, and terminal alkyl-modified polyvinyl alcohol; polyvinyl acetates such as polyvinyl acetate and ethylene-modified polyvinyl acetate; starches such as starch, enzyme-modified starch, thermochemically modified starch, oxidized starch, esterified starch, etherified starch (e.g., hydroxyethylated starch), and cationized starch; cellulose ethers and derivatives thereof such as hydroxyethyl cellulose, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and acetyl cellulose can be used. [Example]

[0023] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Furthermore, unless otherwise specified in this specification, concentrations, parts, etc. are by weight, and numerical ranges are stated as including their endpoints.

[0024] Evaluation method Seat weight Measurement was carried out in accordance with JIS P8124. Thickness Measurements were taken based on JIS P8118:2014. ·density It was calculated from the basis weight and density.

[0025] Wet tensile strength The samples were immersed in water for 1 hour and measured in accordance with JIS P8135. Evaluation was based on the following criteria. ○: Wet tensile strength is 2.0 kN / m or more ×: Wet tensile strength less than 2.0 kN / m

[0026] Water absorption per unit area (TWA) The paper drain was cut into a 7.5 cm x 7.5 cm square and left to stand in a 60°C dryer for 24 hours or more to obtain a bone-dried sample, and the mass of this bone-dried sample was measured (mass after bone drying). The bone-dried sample was immersed in distilled water for 2 minutes, and then placed in a container saturated with water vapor (RH 100%) with one corner of the sample at the top, and hung in an extended state by supporting this top and the two adjacent corners.The sample was then left for 30 minutes, and the mass was measured after draining. Then, the difference between the mass after draining and the mass after drying (mass after draining - mass after drying) was calculated. 2 Water retention capacity per unit (g / m 2 ) and evaluated according to the following criteria. 〇: TWA is 300g / m 2 End ×: TWA is 300g / m 2 less than ·cobb water absorption The surface of the paper drain was measured for 120 seconds according to JIS P8140.

[0027] Preparation of paper substrate (Paper base material 1) To each raw sample, an internal paper strength enhancer (PAM), an internal sizing agent (rosin-based), and a wet strength agent were added in amounts of 0.5%, 0.1%, and 0.5% by pulp, respectively. A back layer consisting of 100% corrugated recycled paper pulp, a middle layer consisting of 100% recycled paper pulp, and a top layer consisting of 70% unbleached kraft pulp and 30% corrugated recycled paper pulp were combined in a weight ratio of back layer:middle layer:top layer = 25:60:15. After drying in a dryer, a water repellent agent containing paraffin wax and rosin was applied to one side of the top layer, and after drying again in a dryer, the paper was smoothed using a calendar to produce paper base 1 (basis weight: 280.0 g / m 2 Surface COBB water absorption (120 seconds): 13.9 g / m 2 , Water repellent coating amount: approx. 1g / m 2 ) was manufactured.

[0028] (Paper base material 2) The back layer, middle layer, and surface layer, each made of 100% recycled magazine paper pulp, were combined in a weight ratio of back layer: middle layer: surface layer = 25:60:15, dried in a dryer, and smoothed using a calendar to produce paper base material 2 (basis weight: 350.0 g / m 2 Surface COBB water absorption (120 seconds): 421g / m 2 ) was manufactured.

[0029] (Paper base material 3) To each raw sample, an internal paper strength agent (PAM) and an internal sizing agent (rosin-based) were added at 0.5% and 0.1% by weight of pulp, respectively. A back layer consisting of 100% corrugated recycled paper pulp, a middle layer consisting of 100% recycled paper pulp, and a surface layer consisting of 70% unbleached kraft pulp and 30% corrugated recycled paper pulp were combined in a weight ratio of back layer:middle layer:surface layer = 25:60:15. After drying with a dryer, the paper was smoothed using a calendar to produce paper base material 3 (basis weight: 279.2 g / m 2 Surface COBB water absorption (120 seconds): 31.1 g / m 2 ) was manufactured.

[0030] (Paper base material 4) Coaster base paper (manufactured by Nippon Paper Industries Co., Ltd., basis weight: 570 g / m 2 Surface COBB water absorption (120 seconds): 942 g / m 2 ) was used as paper substrate 4. (Paper base material 5) Kimtowel (manufactured by Nippon Paper Crecia Co., Ltd., basis weight: 76 g / m 2 The surface COBB water absorbency (120 seconds: water penetrates and cannot be measured) was determined as paper substrate 5.

[0031] Preparation of paper drains A 210cm x 297cm sample was cut from each paper substrate and applied to the substrate either as is or in the layering order shown in the table with adhesive (PVA110, manufactured by Kuraray Co., Ltd., coating weight 5g / m2 solids). 2 ) and then a pressure of 2kN was applied for 1 minute using a press to create a paper drain.

[0032] [Table 1]

[0033] The paper drains of the present invention obtained in Examples 1 to 13 have a wet tensile strength of 2.0 kN / m or more and a TWA of 300 g / m 2 As described above, they were excellent in durability and drainage. Among them, Examples 2, 5 to 7, and 11 to 13 were particularly excellent in durability, which allowed them to withstand long-term use. Furthermore, Examples 4 to 6, 8 to 9, and 11 to 12 were particularly excellent in drainage efficiency, which allowed them to efficiently drain water from soft ground. Of the paper drains of the present invention obtained in Examples 1 to 13, Examples 5, 6, 11, and 12 were excellent in the balance between durability and drainage, and Examples 5 and 6 were particularly excellent. Comparative Examples 1 and 6 have a wet tensile strength of 2.0 kN / m or more, but a TWA of 300 g / m 2 In addition, in Comparative Examples 2, 4 to 5, 7 and 9, the TWA was 300 g / m 2 Although the wet tensile strength was less than 2.0 kN / m, the durability was poor. Furthermore, Comparative Examples 3 and 8 had a wet tensile strength of less than 2.0 kN / m and a TWA of 300 g / m. 2 and was inferior in both durability and drainage.

Claims

1. having one or more paper substrates, Wet tensile strength of 2.0 kN / m or more, water absorption per unit area (TWA) of 300 g / m ２ A paper drain characterized by the above.

2. 2. The paper drain according to claim 1, wherein two or more paper substrates are bonded together.

3. Cobb water absorption (120 seconds) is 300 g / m ２ 3. The paper drain according to claim 1, wherein the paper substrate is:

4. Cobb water absorption (120 seconds) is 300 g / m ２ a first paper substrate, which is Water absorption per unit area (TWA) is 300g / m ２ The second paper substrate as described above; 3. The paper drain according to claim 2, further comprising:

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