KR100603073B1 - Mulching-paper for agriculture and process of producing thereof - Google Patents

Abstract

In the present invention, in the mulching paper for agriculture, the aqueous dispersion of the degradable polyester resin having a viscosity of 100 to 500 cps and a solid content of 10 to 40% is coated on one or both sides of the paper, and the machine direction wet thermal sheet is 0.5 to 2 km, Agricultural mulching paper, characterized in that the basis weight is 40 to 90g / ㎡ and a method for manufacturing the same, which can be used for the purpose of weeding without the distinction of paddy field by replacing the raw material of the coating process, one of the existing paper manufacturing process with water-soluble degradable polymer It is to provide a method for manufacturing agricultural mulching paper.

When the mulching paper of the present invention is used to cultivate crops, it is decomposed in a natural state, thus no collection work is required, there is no soil and water pollution, no impact on the growth of subsequent crops, and environmentally friendly agriculture such as rural labor saving can be performed. .

Description

Mulching paper for agriculture and manufacturing method thereof

The present invention relates to mulching paper using a polymer aqueous dispersion that is decomposed in soil and / or water for the purpose of weed control, and a method for producing the same. There is an increasing demand for agricultural products using organic farming methods, due to the growing interest in environmental protection and safe farm products. As a result of organic farming, farmers are replacing synthetic fertilizers with organic fertilizers, and if they use varieties that are resistant to pests, they can grow organically enough with a slight yield reduction.

However, the biggest disadvantage of organic farming is that weed control is not easy. Mulching cultivation technology using non-degradable polyethylene film has been developed as a means to remove weeds without depending on herbicides and manpower, but it has to be collected after use. There is a disadvantage that can not be used for paddy farming. In order to overcome the disadvantages of the polyethylene film, a basis weight of 150 g / m 2 or more paper is used for the purpose of weeding, which has a weak disadvantage in water and is easily decomposed into fibers when applied to non-farming, so it is not effective for weed control.

Prior arts related to degradable mulching agricultural materials include collapsible mulching films made by adding photodegradation catalysts or biodegradable plastics to non-degradable polyethylene, mulching papers made by adding organic or inorganic materials, and mulching mats coated with biodegradable polymers on paper. have.

Polyethylene film has excellent properties in terms of light transmittance, temperature rise effect, weed control and strength, but it does not decompose and remains a fatal weakness in soil and water environment, which has a big limitation as a mulching agricultural material for disposable crops. In order to improve this, as an example of a collapsible mulching film, Korean Patent Application No. 96-064953 and US Patent No. 5,384,183 describe bio / photodegradable agricultural mulching films. This mulching film is made by mixing biodegradable aliphatic polyester with non-degradable polyethylene or using a photodegradable titanium oxide catalyst to enhance the degradability while maintaining the advantages as a mulching film. However, non-degradable polyethylene remaining after 3 months to 1 year of agriculture causes problems such as lower root growth of subsequent crops and adversely affect soil drainage.

To overcome the non-degradability of the polyethylene, Japanese Journal of Crop Science 1997, 66 (4) 710 ~ 713, Korea Journal of Weed Science 1997, 17 (4), 368 ~ 374 , Korean Journal of Crop Science 2000, 45 (3), 216 ~ 219, Japanese Patent Application Publication No. 4-264258, Korean Patent Registration No. 20-0207043, etc. have. Mulching papers are environmentally friendly, biodegradable, and have the advantage of recycling waste paper and / or waste paper, but they have weak breaking strength and are easily broken down into fiber in fresh water and have a basis weight of 150g / ㎡ or more. There is a disadvantage that does not adhere.

     Some reinforce the paper's paper strength by using a paper enhancer such as rosin, polyacrylamide, cationic starch, epoxy, or by mixing rice straw and pulp as in Korean Patent Application No. 2001-0111469. However, this also does not overcome the disadvantages of soil adhesion or degradation to fiber in fresh water for more than two months.

In order to solve the problems of the above-mentioned non-degradable polyethylene and a paper having a low wettability at the same time, in Korea Patent Application No. 2002-0079217, a multi-layered mulching mat was developed by extrusion coating biodegradable polymer on newspaper paper. This cumbersome and high manufacturing cost makes mass production difficult and economical for farmers to use.

Therefore, the object of the present invention is to use the decomposable polymer aqueous dispersion as a raw material of the coating process, which is part of the paper manufacturing process in view of the above-mentioned problems of the prior art, the manufacturing process is simple and the strength is improved so that it is not easily decomposed into fiber in the answer. It provides agricultural mulching paper and a manufacturing method thereof.                         

It is another object of the present invention to provide a mulching paper and a method for producing the same, suitable for agriculture, which does not require a separate collection operation and does not require any separate collection work due to the basic weed control effect of mulching agricultural materials and natural mulching within a few months after mulching. It is a task.

       Therefore, according to the present invention, there is provided an agricultural mulching paper, characterized in that the degradable polyester resin aqueous dispersion having a viscosity of 100 to 500 cps and a solid content of 10 to 40% is coated on one or both sides of the paper.

Hereinafter, the present invention will be described in more detail.

The paper used in the present invention is not affected by the material because all of the general paper composed of cellulose as a main ingredient and paper, paper, waste paper, waste paper, etc. can be dissociated in a pulp state and then used again. In order to increase the paper strength of the paper, the present invention is coated with a decomposable polymer aqueous dispersion so as to have a thickness of 5 to 15 μm using a coating machine in the papermaking process so that the basis weight becomes 40 to 90 g / m 2. It is characterized by being decomposed in nature after being produced. In addition, the agricultural mulching paper is characterized in that the machine direction wet thermal shear is 0.5 to 2km is configured to give a mulching effect in a certain period of time in the open or fresh water where the actual crop cultivation is performed.

Degradability as used in the present invention includes the meanings of biodegradability, photodegradability, biodegradability, hydrolyzability and the like. The characteristics of the degradable polymer coated on the agricultural mulching paper should be water-soluble and the decomposition period is controlled and must proceed at a rapid rate during decomposition. Generally, water-soluble and degradable polymers include polyvinyl alcohol, polyvinylpyrrolidone, etc., but the decomposition period is one year or longer, and thus it is unreasonable to be applied to the present invention.

Preferred examples of the degradable polymer having a decomposition period of less than one year used in the present invention are monomers containing sulfonate groups in the degradable polyester resin of formula 1 having R 1 and R 2 or the polyester resin of formula 2 having R 3 And degradable polyesters copolymerized.

Monomers used in the preparation of the polycondensed aliphatic or cycloaliphatic polyester of the general formula (1) in the present invention are ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,4- At least one alcohol selected from the group consisting of cyclohexane dimethanol and at least one carboxylic acid selected from the group consisting of oxalic acid, succinic acid, adipic acid, dimethyl succinate, dimethyl adipate, terephthalic acid, isophthalic acid and dimethyl terephthalic acid have. Monomers used in the preparation of the ring-opening polymerized aliphatic polyester of Formula 2 include caprolactone, lactide, glycolide, and the like.

      The polyester of Formula 1 thus obtained is polybutylene succinate which is polyethylene succinate, polybutylene succinate, polybutylene adipate, and polybutylene succinate-adipate copolymer, aliphatic and aromatic copolyester. Nate-ethylene terephthalate copolymer, polybutylene adipate-ethylene terephthalate copolymer, polyhydroxy butyrate represented by the repeating unit of formula (polyhydroxy-

butylate, polyhydroxyvaleate, polylactic acid and copolymers thereof, polycaprolactone and the like.

(In Formula 1, n is a repeating unit, and R ₁ and R ₂ are aliphatic or alicyclic hydrocarbons having 2 to 6 carbon atoms.)

(In Formula 2, m is a repeating unit and R ₃ is an aliphatic hydrocarbon having 2 to 6 carbon atoms.)

The degradable polyesters represented by Chemical Formulas 1 and 2 do not dissolve or disperse in water, and thus are difficult to apply directly to the present invention. Therefore, in the present invention, in order to impart water solubility, a hydrophilic degradable polyester is copolymerized with 5-sodiumsulfoisophthalic acid and its derivatives, sulfosuccinic acid, and glutaldehyde sodium bisulfite addition compound. A resin can be obtained. The water-soluble monomer may be used in an amount of 0.5 to 15 mol% based on the total molar ratio, but less than 0.5 mol% does not dissolve in water. . A decomposable polyester resin obtained by using a monomer containing 0.5 to 15 mol% of sulfonate groups is dispersed in water so that the solid content is 10 to 40%, and the viscosity of the dispersion is 100 to 500 cps to prepare a coating solution. When the solid content of the degradable polyester aqueous dispersion used in the coating process is less than 10%, the thickness of the degradable polyester resin layer dried after coating is low and the strength is low, so that the synergistic effect of the wet strength pursuant to the present invention cannot be obtained. If it exceeds 40%, the thickness of the degradable polyester resin layer dried after coating may be thick, resulting in an increase in decomposition time. In addition, if the viscosity of the aqueous dispersion is too low, coating of the coating solution is not made well, if the viscosity of the aqueous dispersion is too high may cause a problem that the production flow of paper produced at a high speed of 1000m / hour or more is broken.

In general papermaking process, the paper is sprayed on a paper machine in a headbox in which water, paper fibers, fillers, and various additives are mixed to form a wetland, and a basic paper is formed through a pressurized dehydration dryer. Then, one or both sides of the paper is coated using a coating machine that can perform roll coating, spray coating, blade coating, etc., and then calendered to form a complete paper.

In general, the purpose of coating on paper is to improve the printability and gloss, but in the present invention, the water-soluble biodegradable polyester aqueous dispersion having a viscosity of 100 to 500 cps and a solid content of 10 to 40% has a single coating thickness of 5 to 15 When the coating process of coating on one or both sides of the paper to be μm can produce a mulching paper with excellent wet strength and can be applied to a general papermaking process, there is an advantage that no separate equipment is required. In addition, in the present invention, organic and / or inorganic compounds for adding various functionalities to the mulching paper may be further added to the stock in the headbox. Examples include at least one extender selected from the group consisting of calcium carbonate, talc, elvan, starch, palm bark, rhododendron shell, clam shell and ginkgo biloba or in the group consisting of charcoal, urea, ammonium salts, nitrates, phosphates, molybdenum salts and borate salts. The mulching paper may be prepared by selecting one or more combinations of one or more selected plant fertilizer components and adding them to the aqueous dispersion. If the paper is used as a mulching for agricultural use has the advantage that do not give fertilizer during the mulching.

Hereinafter, the present invention will be described in detail with reference to examples, but the following examples are merely illustrative and are not intended to limit the protection scope of the present invention to the following examples.

Example 1

472 kg succinic acid (HOOC (CH ₂ ) ₂ COOH), 194 kg adipic acid (HOOC (CH ₂ ) ₄ COOH), 1,4-butanediol (1,4-butanediol, HO 600 kg of (CH ₂ ) ₄ OH, sulfosuccinic acid, 59 kg of a 70% aqueous solution of HOOCCH ₂ CH (SO ₃ H) COOH, and 0.43 kg of tetrabutyl titanate as a catalyst were mixed, and the temperature was raised to 200 ° C. in a nitrogen stream. After the transesterification reaction, 0.43 kg of tetrabutyl titanate as a catalyst and 0.41 kg of trimethyl phosphate as a stabilizer were added to slurry in 1,4-butanediol, and the mixture was added at 230 ° C. After mixing well, condensation polymerization was carried out for 4 hours at a pressure of 0.3 mmHg while gradually raising the temperature to 250 ° C., and then discharged to obtain a water-soluble biodegradable polyester having a number average molecular weight of 30,000. At ℃ The mixture was stirred for 5 hours to form an aqueous dispersion having a viscosity of 120 cps and a solids content of 25% .The aqueous dispersion was coated on one surface of the paper in the coating process of the paper manufacturing process so that the coating thickness was 7 μm, and the width was 1,900 mm and the total thickness was 72 μm. Mulching papers having a basis weight of 54 g / m 2 were prepared.

Example 2

A water-soluble biodegradable polyester having a number average molecular weight of 27,000 was obtained by the same procedure as in Example 1 except that 448 kg of succinic acid and 119 kg of a 70% aqueous solution of sulfosuccinic acid were used. The biodegradable polyester thus obtained was stirred at 35 ° C. for 3 hours to form an aqueous dispersion having a viscosity of 180 cps and a solid content of 33%. The prepared aqueous dispersion was coated on one surface of the paper in the coating process of the paper manufacturing process so that the coating thickness was 7 μm, thereby preparing mulching paper having a width of 1,900 mm, a total thickness of 72 μm, and a basis weight of 55 g / m 2.

Example 3

A water-soluble biodegradable polyester having a number average molecular weight of 21,000 was obtained in the same manner as in Example 1 except that 498 kg of succinic acid, 564 kg of 1,4-butanediol, and 123 kg of glutaraldehyde sodium bisulfite were used. The biodegradable polyester thus obtained was stirred at 35 ° C. for 2 hours to form an aqueous dispersion having a viscosity of 110 cps and a solid content of 21%. The prepared aqueous dispersion was coated on one surface of the paper in the coating process of the paper manufacturing process so that the coating thickness was 7 μm to produce mulching paper having a width of 1,900 mm, a total thickness of 72 μm, and a basis weight of 58 g / m 2.

Example 4

A water-soluble biodegradable polyester having a number average molecular weight of 17,000 was obtained by the same procedure as in Example 2, except that 38 kg of 5-sulfoisophthalic acid and 51 kg of 70% aqueous sulfosuccinic acid were used. The biodegradable polyester thus obtained was stirred at 35 ° C. for 2 hours to form an aqueous dispersion having a viscosity of 210 cps and a solid content of 38%. The prepared aqueous dispersion was coated on the surface of the paper in the coating process of the paper manufacturing process so that the coating thickness was 7 μm to produce mulching paper having a width of 1,900 mm, a total thickness of 72 μm, and a basis weight of 61 g / m 2.

Example 5

Example 1 to uniformly mix 75% by weight of cellulose-based pulp, 20% by weight of liquor, 3% by weight of gannetite, and 2% by weight of urea, and then compress and dry according to a conventional paper manufacturing method to enhance wet strength. The aqueous dispersion used in was coated on one surface of the paper in the coating process to prepare a mulching paper of width 1900mm, total thickness 84㎛, basis weight 73g / ㎡.

Comparative Example 1

       Biodegradable polyester having a number average molecular weight of 36,000 was obtained by the same procedure as in Example 1 except that 498 kg of succinic acid, 194 kg of adipic acid and 600 kg of 1,4-butanediol were used. The biodegradable polyester thus obtained was processed by melt coating to extrude the rolled recycled paper (thickness 65㎛, basis weight 50g / m2, PanAsia Korea) through t-die (T-Dies) at 250 ℃. mm, total thickness 70㎛, mulching mat of a basis weight 56g / ㎡ was prepared.

Comparative Example 2

Newspapers having a basis weight of 48 g / m 2 were used for mulching.

Comparative Example 3

Kraft paper having a basis weight of 120 g / m 2 was used for mulching.

Thermal shortening (tensile strength in the machine direction) was evaluated for dry conditions and wet conditions in which the construction products of Examples 1 to 5 and Comparative Examples 1 to 3 were immersed for 1 day, respectively. In addition, after using the rice transplanter which can cut and install each construction into 200m length rolls, the rice seedlings were treated by rice transplanting, and the degradation period, soil adhesion, and weed control value (%) were evaluated by the following method. . The evaluation results are presented in Table 1.

* Basis weight: measured by the method of KS M 7013.

Thermal shortening: measured by the method of KS M 7014.

* Machine direction wet thermal shearing: The specimen of KS M 7014 was measured after sufficiently wetted with water.

* Decomposition period: From the day of transplantation, the presence of mulching paper was visually observed. * Weed control: Weed in Formula 1 by comparing the dry weight of weeds generated from weed control areas (untreated areas) without mulching mat coating and weeds generated from weed control areas (treatment areas) coated with mulching mats. The control price is calculated (%).

    Weed control value (%) = [1-(treated weed building weight) / (untreated weed building weight)] × 100

* Soil adhesion by mulching mat: Observed and evaluated visually soil adhesion after 1 month after suppression on the pavement.

 (Evaluation grade: ◎ Very good, O good, △ Normal, X bad)

division Basis weight (g / ㎡) Thermal insulation (km) Decomposition period (days) Soil adhesion Weed Control Price (%) dry Wet Yun Example 1 54 4.8 1.1 65 ◎ 90 Example 2 55 4.9 1.6 77 ◎ 93 Example 3 58 4.3 1.3 63 O 89 Example 4 61 4.6 0.8 58 ◎ 84 Example 5 73 5.2 1.0 59 ◎ 88 Comparative Example 1 56 4.2 1.4 71 △ 95 Comparative Example 2 48 4.1 N.A 20 N.A N.A Comparative Example 3 120 10.8 N.A 43 N.A N.A

※ N.A. Means no measurement.

As described above, when the paper coated with the degradable polymer aqueous dispersion is used for mulching, it is completely decomposed within several months, thereby providing excellent weed control value without generating environmental pollution, and improving the mechanical workability and soil adhesion at the time of coating. Characteristic, it can be easily applied to the paper manufacturing process can be produced in large quantities in a short time, has the advantages of low cost and light weight, easy to use.

Claims (11)

An agricultural mulching paper, wherein a water-soluble decomposable polyester resin dispersion having a solid content of 10 to 40% and a viscosity of 100 to 500 cps is coated on one or both sides of paper. The method of claim 1, The degradable polyester resin aqueous dispersion is coated on paper with a thickness of 5 to 15 ㎛, agricultural mulching paper, characterized in that the basis weight is 40 ~ 90g / ㎡. The method of claim 1, Agricultural mulching paper, characterized in that the machine direction wet thermal sheet of the agricultural mulching paper is 0.5 to 2km. The method of claim 1, The degradable polyester resin is an agricultural mulching paper, characterized in that the copolymer of the sulfonate group containing 0.5 to 15 mol% of the resin of formula (1) or the resin of formula (2).

(In Formula 1, n is a repeating unit, and R ₁ and R ₂ are aliphatic or alicyclic hydrocarbons having 2 to 6 carbon atoms.)

(In Formula 2, m is a repeating unit and R ₃ is an aliphatic hydrocarbon having 2 to 6 carbon atoms.) The method of claim 4, wherein The monomer containing a sulfonate group is an agricultural mulching paper, characterized in that at least one of 5-sodium sulfoisophthalic acid and derivatives thereof, sulfosuccinic acid and glutaraldehyde sodium bissulphite additive. The method of claim 4, wherein The polyester resin of Formula 1 is at least one alcohol and oxalic acid selected from the group consisting of ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,4-cyclohexanedimethanol Agricultural mulching paper characterized in that the polymerization of at least one carboxylic acid selected from the group consisting of succinic acid, adipic acid, dimethyl succinate, dimethyl adipate, terephthalic acid, isophthalic acid and dimethyl terephthalic acid. The method of claim 4 Polyester of Formula 2 is an agricultural mulching paper, characterized in that the ring-opening polymerization of caprolactone, lactide or glycolide. The method of claim 4, wherein The polyester resin of Formula 1 is polyethylene succinate, polybutylene succinate, polybutylene adipate, polybutylene succinate- adipate copolymer, polybutylene succinate- ethylene terephthalate copolymer and polybutyl Agricultural mulching paper, characterized in that the one selected from the group consisting of ren adipate-ethylene terephthalate copolymer. The method of claim 4, wherein The polyester resin of Formula 2 is an agricultural mulching paper, characterized in that one selected from the group consisting of polyhydroxybutylate, polyhydroxyvalate, polylactic acid and copolymers thereof and polycaprolactone. The method of claim 1, In paper, one or more extenders selected from the group consisting of calcium carbonate, talc, elvan, starch, palm bark, rhododendron shell, clam shell and ginkgo leaf or in the group consisting of charcoal, urea, ammonium salt, nitrate, phosphate, molybdenum salt and borate Agricultural mulching paper, characterized in that produced by further adding one or more selected plant fertilizers. An agricultural mulching paper comprising a coating process for coating on one or both sides of the paper so that the one-side coating thickness is 5 to 15 μm with an aqueous dispersion of a decomposable polyester resin having a solid content of 10 to 40% and a viscosity of 100 to 500 cps. Manufacturing method.