TW202425793A - Ground-covering paper for farming - Google Patents

Abstract

The present invention provides an agricultural floor covering paper with excellent strength, durability and workability. The agricultural floor covering paper of the present invention comprises pulp and chemical fiber. The ratio of the chemical fiber exceeds 5% by weight of the total weight of the agricultural floor covering paper. In a preferred example, the basis weight of the agricultural floor covering paper is 20 to 50 g/m ² . In another preferred example, the chemical fiber can be either or both of vinyl fiber and rayon fiber.

Description

Agricultural floor covering paper

The present invention relates to an agricultural floor covering paper. This application is based on and claims priority to Japanese Patent Application No. 2022-200336 filed with the Japan Patent Office on December 15, 2022, and its contents are cited herein.

In dry farming, plastic film is used to cover the fields. The use of film sheets to suppress weeds and control ground surface temperature is widely practiced. However, since the film sheets do not decompose in the soil, they remain in the fields after the crops are harvested. In order to plant the next time, the film sheets need to be recovered from the fields. This recovery operation is a great burden for agricultural workers. In addition, since the recovered film sheets are disposed of as industrial waste, the disposal costs also become a great burden.

In the recent process of plastic removal and environmental awareness, a cover sheet has been proposed that can be integrated into the soil and decomposed in the soil after the crops are harvested. For example, a film cover sheet containing biodegradable plastic has been commercially available. However, the film cover sheet containing biodegradable plastic has the disadvantage of deteriorating over time due to hydrolysis.

Several paper covers have also been proposed (e.g., Patent Documents 1 and 2). However, in order to maintain strength and durability against soil bacteria, the basis weight of paper covers needs to be increased. Therefore, previous paper covers are thicker and heavier than film covers. In the above-mentioned previous paper covers, the operating efficiency is reduced when covering dry fields or huts with agricultural machinery called mulchers. Due to these circumstances, although paper covers have advantages in terms of operation, cost, and environment, they have not yet been fully popularized. [Prior Technical Documents] [Patent Documents]

[Patent Document 1] Japanese Patent No. 2762005 [Patent Document 2] Japanese Patent No. 2879650

[The problem the invention is trying to solve]

The present invention provides an agricultural floor covering paper with excellent strength, durability and workability. [Technical means to solve the problem]

[1] An agricultural floor covering paper comprising pulp and chemical fibers, wherein the ratio of the chemical fibers exceeds 5% by weight of the total weight of the agricultural floor covering paper. [2] The agricultural floor covering paper as described in [1], wherein the chemical fibers are either or both of vinyl fibers and rayon fibers. [3] The agricultural floor covering paper as described in [1] or [2], wherein the pulp comprises unbleached pulp. [4] The agricultural floor covering paper as described in any one of [1] to [3], further comprising either or both of a dry paper strength agent and a wet paper strength agent. [5] The agricultural floor covering paper as described in any one of [1] to [4], wherein the basis weight is 20 to 50 g/m ² . [Effects of the Invention]

According to the present invention, an agricultural floor covering paper having excellent strength, durability and workability is provided.

The longitudinal direction of the agricultural floor covering paper is defined as the length direction of the agricultural floor covering paper. The transverse direction of the agricultural floor covering paper is defined as the direction perpendicular to the length direction of the agricultural floor covering paper. In this specification, "～" indicating a numerical range means that the numerical values recorded before and after it are included as the lower limit and upper limit. The lower limit and upper limit of the physical property values disclosed in this specification can be arbitrarily combined to form a new numerical range.

Agricultural floor covering paper contains pulp and chemical fiber. Agricultural floor covering paper preferably further contains one or both of dry paper strength agent and wet paper strength agent. Agricultural floor covering paper may further contain other ingredients besides pulp, chemical fiber, dry paper strength agent and wet paper strength agent as long as it is within the scope that does not damage the effect of the invention. The details and preferred embodiments of agricultural floor covering paper are described below.

(Pulp) Pulp has cellulose fiber as its main component. Examples of pulp include, but are not limited to, chemical pulp, semi-chemical pulp, mechanical pulp, non-wood fiber pulp, and waste pulp. Pulp may be used alone or in combination of two or more. In addition, the wood used as the raw material of pulp may be coniferous wood or broad-leaved wood, or they may be used in combination.

Examples of chemical pulp include kraft pulp (KP), sulfite pulp (SP), and alkaline pulp (AP). Examples of semi-chemical pulp include semi-chemical pulp (SCP) and chemical groundwood pulp (CGP). Examples of mechanical pulp include groundwood pulp (GP), thermomechanical pulp (TMP, BCTMP), and refined groundwood pulp (RGP). Examples of non-wood fiber pulp include pulp produced chemically or mechanically from non-wood fibers such as paper mulberry, safflower, hemp, and kenaf. Examples of waste paper pulp include: decomposed waste paper pulp, decomposed/deinked waste paper pulp, decomposed/deinked/bleached waste paper pulp. Examples of waste paper as a raw material of waste paper pulp include: tea waste paper, kraft envelope waste paper, magazine waste paper, newspaper waste paper, leaflet waste paper, office waste paper, corrugated cardboard waste paper, white waste paper, Kent waste paper, imitation waste paper, and stamp waste paper. However, the pulp is not limited to the above examples.

Among them, as the pulp, unbleached pulp is preferred. Unbleached pulp contains more lignin. Therefore, resistance to soil bacteria becomes higher. As a result, agricultural floor covering paper with further excellent durability (corrosion resistance) is easily obtained. As the unbleached pulp, for example, conifer unbleached kraft pulp (NUKP) and broad-leaved unbleached kraft pulp (LUKP) are preferred, and NUKP is more preferred.

In particular, unbleached pulp with a high Kappa number is good because it contains more lignin. The Kappa number of unbleached pulp is preferably 60 or more, more preferably 65 or more, and further preferably 70 or more. If the Kappa number of unbleached pulp is above the above lower limit, it is easy to obtain agricultural floor covering paper with excellent strength and durability. The Kappa number is a value measured for pulp extracted from agricultural floor covering paper in accordance with JIS P 8211.

(Chemical fiber) Examples of chemical fiber include regenerated fiber, semi-synthetic fiber, and synthetic fiber. One type of chemical fiber may be used alone, or two or more types may be used in combination. Examples of regenerated fiber include rayon fiber and cuprammonium fiber. Examples of semi-synthetic fiber include acetate fiber and Promix fiber. Examples of synthetic fiber include vinyl fiber, nylon fiber, polyester fiber, acrylic fiber, aromatic polyamide fiber, and polyolefin fiber. However, chemical fiber is not limited to the above examples. Furthermore, one type of chemical fiber may be used alone, or two or more types may be used in combination.

Among them, as chemical fibers, in terms of the balance of strength, durability and environmental protection, either or both of vinyl fiber and rayon fiber are preferred. When vinyl fiber is used as the chemical fiber, in one example, a vinyl adhesive fiber having adhesive properties can be mixed into the vinyl fiber. By using the vinyl adhesive fiber, a paper strengthening effect can be expected.

The average fiber length of chemical fiber is preferably 1 to 10 mm, more preferably 2 to 9 mm, and further preferably 3 to 8 mm. If the average fiber length of chemical fiber is above the lower limit of the above numerical range, it is easy to obtain agricultural floor covering paper with excellent strength and durability. If the average fiber length of chemical fiber is below the upper limit of the above numerical range, it is not easy to cause adverse conditions during papermaking of pulp. The average fiber length of chemical fiber is a value measured in accordance with JIS L 1015.

The fiber density of chemical fiber is preferably 0.3 to 3 dtex, more preferably 0.5 to 2.5 dtex, and further preferably 0.8 to 2 dtex. If the fiber density of chemical fiber is above the lower limit of the above numerical range, it is easy to obtain agricultural floor covering paper with excellent strength and durability. If the fiber density of chemical fiber is below the upper limit of the above numerical range, it is not easy to cause adverse conditions during papermaking of slurry. The fiber density of chemical fiber is the value measured in accordance with JIS L 1015.

(Dry paper strength agent) Dry paper strength agent refers to an agent used to enhance the strength of paper in a dry state. Examples of dry paper strength agents include cationized starch, carboxymethyl cellulose (CMC), and polyacrylamide (PAM). However, dry paper strength agents are not limited to these examples. Dry paper strength agents may be used alone or in combination of two or more.

(Wet paper strength agent) Wet paper strength agent refers to an agent used to suppress the decrease in the strength of paper when the paper is wetted with water. Wet paper strength agent can be used to impart water resistance to rain, snow, etc. to agricultural ground covering paper. Examples of wet paper strength agents include polyamide-epichlorohydrin resin, urea resin, melamine resin, and thermally cross-linked polyacrylamide. However, wet paper strength agents are not limited to these examples. Wet paper strength agents may be used alone or in combination of two or more.

(Physical properties and characteristics) The basis weight of the agricultural floor covering paper of the present invention is preferably 20 to 50 g/m ² , and more preferably 25 to 45 g/m ² . If the basis weight is above the lower limit of the above numerical range, the strength and durability of the agricultural floor covering paper can be easily maintained. If the basis weight is below the upper limit of the above numerical range, the burden of the workers during transportation can be easily reduced. Therefore, the workability can be easily improved. The basis weight is a value measured in accordance with JIS P 8124.

The geometric average of the specific tensile strength in the longitudinal direction and the specific tensile strength in the transverse direction is preferably 30 N·m/g or more, more preferably 40 N·m/g, and further preferably 50 N·m/g or more. If the geometric average is above the above lower limit, the strength of the agricultural floor covering paper is further excellent. There is no particular limitation on the upper limit of the geometric average. The specific tensile strength in the longitudinal direction refers to the value obtained by dividing the tensile strength in the longitudinal direction (kN/m) by the basis weight (g/m ² ). The specific tensile strength in the transverse direction refers to the value obtained by dividing the tensile strength in the transverse direction (kN/m) by the basis weight (g/m ² ). The tensile strength in each direction is a value measured separately in accordance with JIS P 8113.

The geometric average of the specific wet tensile strength in the longitudinal direction and the specific wet tensile strength in the transverse direction of the agricultural floor covering paper is preferably 20 N·m/g or more, more preferably 25 N·m/g. If the geometric average is above the above lower limit, the strength of the agricultural floor covering paper is further excellent. The specific wet tensile strength in the longitudinal direction refers to the value obtained by dividing the wet tensile strength in the longitudinal direction (kN/m) by the basis weight (g/m ² ). The specific wet tensile strength in the transverse direction refers to the value obtained by dividing the wet tensile strength in the transverse direction (kN/m) by the basis weight (g/m ² ). The wet tensile strength is a value measured in accordance with JIS P 8135.

(Composition) The ratio of chemical fiber exceeds 5% by mass of the total mass of agricultural floor covering paper. When the chemical fiber is vinyl fiber, the ratio of vinyl fiber is preferably more than 5% by mass and less than 40% by mass, more preferably 5 to 30% by mass, and further preferably 5 to 20% by mass. When the chemical fiber is rayon fiber, the ratio of rayon fiber is preferably more than 5% by mass and less than 40% by mass, and more preferably 10 to 30% by mass. Since the ratio of chemical fiber exceeds 5% by mass of the total mass of agricultural floor covering paper, the strength and durability of agricultural floor covering paper can be fully maintained. If the ratio of chemical fibers is below the upper limit of the above numerical range, it is easy to obtain agricultural floor covering paper that is better in terms of environmental protection. The durability required for agricultural floor covering paper varies according to the length of the cultivation time of the crops cultivated in the agricultural land. Therefore, the ratio of chemical fibers can be appropriately adjusted within the above range according to the cultivation time of the crops cultivated in the agricultural land.

The ratio of pulp is less than 95% by mass relative to the total of 100% by mass of pulp and chemical fiber. The ratio of pulp relative to the total of 100% by mass of pulp and chemical fiber is preferably 60-95% by mass, more preferably 70-95% by mass, and further preferably 80-95% by mass. If the ratio of pulp is above the lower limit of the above numerical range, it is easy to obtain agricultural floor covering paper that is better in terms of environmental protection. If the ratio of pulp is below the upper limit of the above numerical range, it is easy to obtain agricultural floor covering paper with excellent strength and durability.

With respect to 100 mass % of the agricultural floor covering paper, the total amount of pulp and chemical fiber is preferably 80 mass % or more, more preferably 85 mass % or more, further preferably 90 mass % or more, particularly preferably 95 mass % or more, and most preferably 100 mass %.

The ratio of the dry paper strength agent to the total mass of 100% pulp and chemical fiber is preferably 0-2.0% by mass, more preferably 0-1.5% by mass, and further preferably 0-1.0% by mass. If the ratio of the dry paper strength agent is above the lower limit of the above numerical range, agricultural floor covering paper with excellent strength can be easily obtained. If the ratio of the dry paper strength agent is below the upper limit of the above numerical range, agricultural floor covering paper with excellent quality can be easily obtained.

The ratio of the wet paper strength agent to the total of 100% by mass of pulp and chemical fiber is preferably 0-4.0% by mass, more preferably 0.2-3.5% by mass, and further preferably 0.3-3.0% by mass. If the ratio of the wet paper strength agent is above the lower limit of the above numerical range, it is easy to obtain agricultural floor covering paper with excellent strength and durability (water resistance). If the ratio of the wet paper strength agent is below the upper limit of the above numerical range, it is easy to obtain agricultural floor covering paper with excellent quality.

(Manufacturing method) The manufacturing method of agricultural floor covering paper is not limited in any way. For example, the following method can be cited, namely, papermaking is performed on a pulp containing at least a paper stock, and the paper stock contains pulp and chemical fibers. After papermaking, the paper is dried to obtain agricultural floor covering paper. There is no particular limitation on the papermaking machine. Various papermaking machines can be used. In addition to the paper stock, the pulp can further contain chemicals such as dry paper strength agents and wet paper strength agents. During the manufacturing, for example, the slurry box can be appropriately adjusted so that the basis weight of the agricultural floor covering paper is 20 to 50 g/ ^m2 .

(Mechanism of Action) The agricultural floor covering paper of the present invention described above has improved strength and durability because it contains a sufficient amount of chemical fibers. Since the strength and durability are sufficiently improved with the help of chemical fibers, the basis weight, that is, the weight per unit area, can be kept low. Therefore, the agricultural floor covering paper of the present invention is excellent in strength, durability, and workability. In the agricultural floor covering paper of the present invention, in order to reduce the weight, which is the biggest drawback of previous paper covering sheets, chemical components are formulated into the pulp sheet, so that even a relatively low basis weight can show sufficient strength.

(Application) Agricultural ground covering paper is suitable for ground covering in agriculture. Agricultural ground covering paper can be used in rice farming, paddy fields, dry farming, and tillage. The purpose of ground covering can vary depending on the harvest, for example, it can be weeding, weed suppression, shading, and ground temperature control. [Example]

The following examples are given to illustrate the implementation in more detail, but the present invention is not limited to the following description.

<Measurement Methods and Evaluation Methods> The measurement methods and evaluation methods of paper quality in the following examples are as follows. (Basic Weight) The basic weight is measured in accordance with JIS P 8124.

(Tensile strength) The tensile strength was measured in accordance with JIS P 8113.

(Specific tensile strength) Specific tensile strength is calculated as the geometric average of the specific tensile strength in the longitudinal direction and the specific tensile strength in the transverse direction. The specific tensile strength in the longitudinal direction is the value obtained by dividing the tensile strength in the longitudinal direction by the basis weight. Similarly, the specific tensile strength in the transverse direction is the value obtained by dividing the tensile strength in the transverse direction by the basis weight.

(Wet tensile strength) The wet tensile strength was measured in accordance with JIS P 8135.

(Rolling Weight) The weight of each paper sheet was measured when it was rolled up to a width of 1350 mm and a length of 100 m.

(Durability) After covering the outdoor dry fields with the paper sheets of each example, the surface of the sheets was visually observed after 1 week, 3 months, and 6 months. Based on the observation results, the durability was evaluated according to the following criteria. A (excellent): The original shape of the paper sheet was maintained. B (good): Part of the paper sheet was decomposed, but the shape of the sheet was maintained. C (acceptable): About half of the paper sheet was decomposed, but the shape of the sheet was maintained. D (unacceptable): The paper sheet was decomposed and shattered, and the original shape was not left.

<Raw materials> The abbreviations of the raw materials used in the following examples are as follows. (Chemical fibers) ・ Vinylon fiber: a mixed product with a fiber density of 1.1 dtex and a fiber length of 3 to 7 mm ・Rayon fiber: a mixed product with a fiber density of 1.1 dtex and a fiber length of 3 to 7 mm

(Pulp) ・NUKP ・Corrugated cardboard waste paper

(Pharmaceuticals) ・Dry paper strength agent: polyacrylamide resin ・Wet paper strength agent: polyamine-epichlorohydrin resin

<Examples 1 to 5, Comparative Examples 1 and 2> A paper pulp material containing the composition shown in Table 1 and a chemical was prepared. The amount of chemical used shown in Table 1 is a value relative to 100% by mass of the paper material. The paper pulp material of each example was paper-made using a paper machine to obtain a paper sheet of each example. The measurement results and evaluation results of the paper quality of the paper sheet of each example are shown in Table 1.

[Table 1] Unit Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Comparison Example 1 Comparison Example 2 Paper Vinyl Fiber Quality% 20 15 - 8 12 - 5 Raphium fiber Quality% - - 15 - - - - NUKP Quality% 30 85 85 28 26 - 29 Corrugated cardboard waste paper Quality% 50 - - 64 62 100 66 Pharmaceuticals Dry paper strength agent Quality% 0.5 - - 0.5 0.5 - 0.5 Wet paper agent Quality% 2.1 0.5 0.5 2.1 2.1 2.8 2.1 Paper base weigh g/ ^m2 45 45 45 45 45 115 45 Tensile strength kN/m 3.0 2.7 2.1 2.8 2.9 1.8 3.0 Specific tensile strength N•m/g 66.7 60.0 46.7 62.2 64.4 15.7 66.7 Wet tensile strength kN/m 1.3 1.3 1.0 1.3 1.3 1.2 1.3 Rolling weight kg 6.1 6.1 6.1 6.1 6.1 15.5 6.1 Durability 1 week later A A B B A C C 3 months later A B C C B D D 6 months later B C D D C D D

Compared with the paper sheets of Comparative Examples 1 and 2, the paper sheets of Examples 1 to 5 have better strength, durability after one week, and workability. [Industrial Applicability]

According to the present invention, an agricultural floor covering paper having excellent strength, durability and workability is provided.

Claims (5)

An agricultural floor covering paper comprises pulp and chemical fibers, wherein the ratio of the chemical fibers exceeds 5% by weight of the total weight of the agricultural floor covering paper. The agricultural floor covering paper of claim 1, wherein the chemical fiber is either or both of vinyl fiber and rayon fiber. The agricultural floor covering paper of claim 1, wherein the pulp comprises unbleached pulp. The agricultural floor covering paper of claim 1 further comprises one or both of a dry paper strength agent and a wet paper strength agent. The agricultural floor covering paper of any one of claims 1 to 4, wherein the basis weight is 20 to 50 g/m ² .