JPH1052178A - Sheet for agriculture and horticulture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a sheet for agriculture and horticulture, capable of controlling decay period and improving handleability and labor saving without fear of causing soil pollution by composing the sheet of a fabric obtained by forming a specific biodegradable resin composition. SOLUTION: This sheet comprises a fabric obtained by molding and processing a biodegradable resin composition resin comprising (A) 30-70wt.% starch-based polymer such as allyl-etherified starch which is a melt body having a thermoplastic property and obtained by modifying one or two or more kinds of plant starches, (B) 25-65wt.% copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate with an unsaturated monomer containing no functional group such as ethylene, propylene, isobutylene or styrene and (C) 5-40wt.% aliphatic polyester such as polylactone which is a biodegradable resin having a melting point of <=150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agricultural and horticultural sheet. More specifically, it is made of fiber or film with biodegradability, and when left in the natural world, it is gradually decomposed by moisture and microorganisms and disappears after a certain period of time. The present invention relates to an agricultural and horticultural sheet that can be omitted and environmental pollution due to neglect is extremely low.

[0002]

2. Description of the Related Art In vegetable cultivation and the like, agricultural and horticultural sheets stretched on ridges are used for the purpose of promoting healthy growth of plants by controlling soil temperature and humidity and increasing yield. For this reason, a nonwoven fabric sheet in which polyethylene or the like is colored black or silver, a vinyl chloride sheet, or the like is conventionally used as an agricultural and horticultural sheet.
Since these sheets hardly decompose if left in the natural world, they must be collected after use, and furthermore, there are problems such as pollution of the environment after disposal. Was.

Japanese Patent Application Laid-Open No. 07-123876 proposes a degradable sheet-like composition and molded product comprising a fibrous substance such as paper or pulp and a biodegradable resin, an agricultural sheet and a sheet-like molded product. I have. Although this sheet is biodegradable and strong, it cannot be controlled until the disintegration period. After the period when the use of the sheet is required, it is returned to the soil, collection after use is unnecessary, and the appearance of agricultural and horticultural sheets without concern for environmental pollution is desired. Not obtained.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an agricultural and horticultural sheet in which the disintegration period can be controlled and the decomposed residue does not cause environmental pollution.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that a copolymer of starch-based polymer, vinyl acetate and an unsaturated monomer containing no functional group is copolymerized. It has been found that the disintegration period can be controlled by adding a required amount of an aliphatic polyester to a copolymer obtained by partially hydrolyzing the coalesced polymer, and it has been found that the desired object is achieved, thereby completing the present invention. The present invention has the following configuration. (1) An agricultural and horticultural sheet comprising a fabric obtained by molding and processing a biodegradable resin composition containing the following components (A), (B) and (C), wherein the composition comprises the ( A) is 3
An agricultural and horticultural sheet comprising 0 to 70% by weight, 25 to 65% by weight of (B), and 5 to 40% by weight of (C). (A) Starch polymer (B) Copolymer obtained by partially hydrolyzing a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group (C) Aliphatic polyester (2) A) a nonwoven fabric, a knitted fabric or a woven fabric formed of a biodegradable fiber obtained by spinning a biodegradable resin composition containing the following components (A), (B) and (C); An agricultural and horticultural sheet obtained by laminating sheets, wherein (A) is 30 to 70% by weight, (B) is 25 to 65% by weight, and (C) is 5 to 40% by weight in the composition. % For agricultural and horticultural use. (A) Starch polymer (B) Copolymer obtained by partially hydrolyzing a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group (C) Aliphatic polyester (3) ) Functional sheets are fertilizer-containing sheets, seaweed sheets,
The agricultural and horticultural sheet according to the above item (2), which is at least one selected from a heat-absorbing sheet, a moisture-absorbing sheet, and an insect-proof and antibacterial sheet. (4) The above-mentioned (1) to (1), wherein the starch-based polymer is a thermoplastic melt obtained by modifying at least one kind of plant starch.
(3) The agricultural and horticultural sheet according to any one of the above items. (5) The unsaturated monomer containing no functional group is ethylene,
At least one unsaturated monomer selected from propylene, isobutylene and styrene, wherein the partially hydrolyzed copolymer has a saponification degree of 78 to 98%, and the partially hydrolyzed copolymer The agricultural and horticultural sheet according to the above item (2) or (3), wherein the content of the biodegradable fiber is 25 to 65% by weight. (6) The agricultural or horticultural sheet according to any one of the above (1) to (3), wherein the aliphatic polyester is a biodegradable resin having a melting point of 150 ° C or lower.

Hereinafter, the present invention will be described in detail. Examples of the starch-based polymer of the present invention include corn starch, bracken starch, kuzu starch, potato starch, wheat starch, kissava starch, sago starch,
Thermoplastically homogeneous melts (heat-modified starches) obtained by thermally denaturing at least one of plant starches such as tapioca starch, corn, bean starch, lotus starch, Hishi starch and sweet potato starch are preferred.
It is not particularly limited to these. The thermal denaturation can be performed, for example, by performing a heat treatment at 80 to 290 ° C. under a high pressure of 60 to 300 MPa while maintaining the moisture containing 5 to 30% by weight of starch in a closed space. In addition, the starch-based polymer can be used in the following forms. For example, chemically modified starch derivatives (allyl-etherified starch, carboxymethyl-etherified starch, hydroxyethyl-etherified starch, hydroxypropyl-etherified starch, methyl-etherified starch, phosphoric acid-crosslinked starch, formaldehyde-crosslinked starch) Starch, epichlorohydrin-crosslinked starch, acrolein-crosslinked starch, acetoacetate-starch, acetate-starch, succinate-starch, xatogenate-starch, nitrate-starch, urea-phosphate-starch, phosphate-starch ), Chemically degraded starch (dialdehyde starch, acid-treated starch, hypochlorite oxidized starch, etc.), enzyme-modified starch (hydrolyzed dextrin, enzyme-degraded dextrin, amylose, etc.)
Physically modified starch (α-starch, fractionated amylose, wet heat-treated starch, etc.) can be exemplified, but from the viewpoint of melt extrusion processability, the use of the above-mentioned heat-modified starch is most preferred.

The partially hydrolyzed copolymer used in the present invention is obtained by copolymerizing vinyl acetate with an unsaturated monomer having no functional group such as ethylene, propylene, isobutylene and styrene to form a vinyl acetate group. It is a copolymer obtained by hydrolysis, and the degree of saponification of the copolymer obtained by hydrolysis is 78.
９８98%, more preferably 85% ９８98%, even more preferably 90% ９８98%. The compounding amount of the partially hydrolyzed copolymer is 25 to 65% by weight in the composition in view of biodegradability and processability, and more preferably 35% by weight.
６０60% by weight. As the unsaturated monomer having no functional group, it is preferable to use at least one selected from ethylene, propylene, isobutylene and styrene.

The aliphatic polyester used in the present invention is more preferably a biodegradable resin having a melting point of 150 ° C. or less, such as polycaprolactone, polyethylene succinate, polybutylene succinate, etc. At least one of them can be used. Here, the reason why the melting point is set to be 150 ° C. or less is that it is necessary to perform the processing together with the starch-based polymer.

[0009] The formation into a biodegradable fiber or film comprises:
It is performed at a temperature of 150 ° C. or less. If the temperature is higher than 150 ° C., the starch-based polymer may be dehydrated and foamed inside the molding machine during the molding process, and the moldability may be significantly reduced.

The above-mentioned starch-based polymer and a partially hydrolyzed copolymer are blended, and if necessary, a plasticizer, a matting agent, a pigment, a light stabilizer, a heat stabilizer, an antioxidant, etc. Can be added in a range that does not impair the effects of the present invention. For example, by adding a plasticizer, moldability and spinnability can be improved. Examples of the plasticizer include the following compounds of glycols or ethanolamine. Specifically, ethylene glycol,
Trimethylene glycol, tetramethylene glycol,
Pentamethylene glycol, hexamethylene glycol, propylene glycol, glycerin, 2,3-butadieneol, 1,3-butanediol, diethylene glycol, triethylene glycol, 1,7-heptanediol, cyclohexane-1,2-diol, cyclohexane- Examples thereof include 1,4-diol, pinacol, hydrobenzoin, and benzpinacol.

The fabric referred to in the present invention is a nonwoven fiber aggregate or film selected from nonwoven fabric, knitted fabric and woven fabric.

For example, the biodegradable fibers used to obtain the nonwoven fabric, knitted fabric, and woven fabric that will become the agricultural and horticultural sheet of the present invention are:
It can be manufactured by the following steps. First, melt spinning is performed according to the intended use, and a non-drawn yarn is wound at a take-up speed according to the required fineness. Next, stretching, crimping, and the like are applied as necessary, and the fiber is cut to a fiber length according to the fineness.

The biodegradable fiber of the present invention can improve the carding property by imparting crimp, and can impart bulkiness to a fabric made of crimped fiber. In many cases, a crimping method is used as a means for imparting crimp during the stretching step. The number of crimps is taken into consideration depending on the fineness and fiber length of the fiber, and the number of crimps is preferably 4 to 20 crimps per 25 mm.

The agricultural and horticultural sheet of the present invention is composed of biodegradable fibers mainly composed of a starch-based polymer having no distinct melting point. For example, after the fibers are humidified with steam or the like, the fibers are passed through a through-air processing machine to remove excess water, whereby the adhesiveness becomes sufficient. This utilizes the property that the starch-based polymer wets and swells in the presence of moisture. In addition, as a method of humidifying the starch-based polymer, a method such as steam spraying or immersion in water can be used, but the processing method is not limited thereto.

Further, a non-woven fabric may be formed by blending a fiber composition which causes degradation in the natural world, such as a biodegradable fiber other than the biodegradable fiber which is a constituent fiber of the non-woven fabric, and a photo-degradable fiber.

The agricultural and horticultural sheet of the present invention comprises the biodegradable fiber as a main component. Preferably, the constituent fibers are three-dimensionally entangled. Entanglement can be imparted by needle punching or the like, and when combined with adhesion by moisture, the strength is further improved. However, the processing method is not limited to this.

In a preferred embodiment of the biodegradable fiber,
On the sheath side, a starch-based polymer, a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer containing no functional group, and a resin composition comprising an aliphatic polyester,
On the core side, a composite fiber using a resin composition composed of an aliphatic polyester can also be used.

Examples of the functional sheet used in the present invention include a gel sheet made of sodium alkylate, agarose and the like. Since the gel sheet does not have air permeability, it is preferable to use the gel sheet after opening the sheet to impart air permeability. Further, it is preferable to use as a laminate of nonwoven fabric / medium / nonwoven fabric. Further, a pesticide, a fertilizer, and the like can be added to the gel sheet as needed at the time of preparing the medium.

Another example of the functional sheet is a sheet in which a sustained-release fertilizer "LP Coat" (trademark of Chisso Corporation) is embedded in the sheet in advance. By using the “LP coat”, it is possible to continuously provide fertilizer necessary for growing plants.

In the present invention, the biodegradable fiber can be used as a card web manufactured by using a card machine or an air-laid web using an air array.

The agricultural and horticultural sheet of the present invention is, specifically,
Agricultural and horticultural sheets such as light-shielding sheets, frost-proof sheets, and wind-proof sheets, or agricultural and horticultural sheets for the purpose of keeping moisture and heat.
Alternatively, it can be used for nursery beds, seed beds, etc., but is not limited thereto.

The agricultural / horticultural sheet of the present invention controls the biodegradation rate by combining a resin with a high biodegradation rate and a resin with a low biodegradation rate. In the present invention, a mixture of a starch-based polymer and a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group is used as a resin having a high biodegradation rate. This causes both to swell in the presence of water,
In addition, since biodegradation occurs in soil, the rate of disintegration is high. The starch-based polymer significantly improves the moldability, especially the spinnability of melt spinning, by adding a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group. Can be done. When the fiber or film thus produced is left on the soil, it usually decomposes in about one month, depending on conditions and fineness. Next, an aliphatic polyester is used as the resin having a low biodegradation rate. Fibers made from this resin, when left on the soil, usually decompose in about six months, depending on conditions and fineness. The fibers produced by changing the mixing ratio of the resins having different biodegradation rates have different biodegradation rates depending on the mixing ratio of the resins, and the same can be said for the fabric obtained therefrom. About 0.5 months ~
The biodegradation rate can be controlled within a period of 5.5 months. Further, other degrading factors other than biodegradability that cause the agricultural and horticultural sheet of the present invention to disintegrate include heat storage deterioration, disintegration and destruction performed by pests, animals, and the like. Is also possible.

【Example】

Hereinafter, the present invention will be described in detail by comparing the performance of the embodiment with the comparative example. However, the present invention is not limited to only the following examples.

The definition of the disintegration period and the test method thereof in the present invention are as follows.

A field test was performed to evaluate the present invention. The method is to lay the sheet on the ridge of a field made on the factory premises and expose it to the natural environment. Continue observing the appearance of this sheet and see if more than 50% of the sheet area is torn,
Alternatively, a period until disappearance is defined as a disintegration period and measured.

1. Production of biodegradable fiber Heat-modified corn starch A containing 10% by weight of water, ethylene 3
A partially hydrolyzed copolymer B and polycaprolactone C having a saponification degree of 98% and a copolymer of 0 mol% and 70 mol% of vinyl acetate are each added to the total amount of A, B and C. The pellets were used at a composition ratio calculated so as to decompose within a predetermined period, and mixed and granulated to obtain pellets. The pellets were put into a spinning die having a hole diameter of 0.8 mmφ and a number of holes of 350 and a full flight screw having a compression ratio of 2.0 to perform melt spinning. 0.3% by weight of lauryl phosphate potassium salt as a surface finishing agent was added to the raw yarn thus obtained.
The fibers were attached, crimped at 12 crests / 25 mm with a crimper, and cut to a fiber length of 38 mm to obtain staples of 3 d / f.

2. Method of preparing needle-punched nonwoven fabric After passing a staple through a carding machine to form a web having a basis weight of 40 g / m2, the fibers are entangled using a known needlepunching method and solidified. Thereafter, heat treatment is performed to further increase the adhesiveness.

3. Card web-Nonwoven fabric preparation method by heat treatment After staples are passed through a card machine to form a web with a basis weight of 40 g / cm2, the web is subjected to 2 kgf / cm2 if necessary.
Is applied for 5 seconds, and then heat treatment is performed for 10 seconds with a through-air processing machine set at 100 ° C. to fuse the fibers. The obtained nonwoven fabric can be cut to the size to be used, and can be used as a sample or a part of the sample.

4. Non-woven fabric production method using a heat roll 7m using the card machine
/ Min. At a speed of 40 min / min. The obtained web was heated at a speed of 7 m / min using an embossing roll having a bonding area ratio of 24% and heated at a heating temperature of 6%.
Nonwoven fabric processing was performed at 0 ° C.

5. Knitted fabric manufacturing method 0.3% by weight of lauryl phosphate potassium salt was attached to the biodegradable fiber obtained in
A 2d / f staple is obtained by giving a crimp of crests / 25 mm and cutting to a fiber length of 51 mm, and this staple is made into a spun yarn of cotton count 48/1 by ordinary worsted spinning. Using this spun yarn, a warp density of 20 yarns / inch and a weft density of 2
0 / inch plain woven fabric was produced.

Example 1 Resins were blended at a weight ratio of A = 35, B = 60, C = 5% by weight to obtain a biodegradable resin composition. Using this, fiberization was performed. After making this fiber into a web, an agricultural and horticultural sheet was obtained by a needle punch nonwoven fabric method / through-air processing. Using this, a field test was performed, and the disintegration period was measured (the results are shown in Table 1).

Example 2 Resins were blended in a weight ratio of A = 35, B = 35, C = 30% by weight to obtain a biodegradable resin composition. The fiber produced using this was used as an agricultural and horticultural sheet and processed and evaluated in the same manner as in Example 1 (the results are shown in Table 1).

Example 3 A resin was blended at a weight ratio of A = 35, B = 25, C = 40% by weight to obtain a biodegradable resin composition. The fiber produced using this was used as an agricultural and horticultural sheet and processed and evaluated in the same manner as in Example 1 (the results are shown in Table 1).

Example 4 A biodegradable resin composition obtained by blending resins in a weight ratio of A = 35, B = 25, C = 40% by weight was used on the sheath side and polyethylene succinate on the core side. A conjugate fiber having a sheath-core area ratio of 5: 5 in a fiber cross-sectional area in a direction perpendicular to the fiber length was produced. This fiber was used as an agricultural and horticultural sheet, and processed and evaluated in the same manner as in Example 1 (the results are shown in Table 1).

Example 5 10 g of Bacto-tryptone was added to Bacto-tryptone.
5 g of yeast extract and 5 g of NaCl were dissolved in 1 liter of distilled water (pH was adjusted with sodium hydroxide).
After adjusting the amount to 7.5), agarose was added in an amount of 1.5%, and the solution dissolved in an autoclave was solidified to a thickness of 0.5 cm to form a sheet. A sheet having perforations of 25 cm or more in total area per 100 cm of the sheet was defined as a medium sheet. Next, a culture medium sheet was overlapped between the sheets prepared in Example 2, and the disintegration was evaluated (the results are shown in Table 1).

Example 6 A raw yarn was produced by using a resin blended at a weight ratio of A = 35, B = 60, C = 5% by weight as a raw material by a method for producing biodegradable fibers. 0.3% by weight of lauryl phosphate potassium salt was adhered to this yarn, and cut to a fiber length of 5 mm. 90% by weight of this fiber and LP coat (an agricultural fertilizer in which a fertilizer is coated with a resin; registered trademark of Chisso Corporation) 10
% By weight in the air to form a web. A sheet was obtained from this web by through-air processing. This sheet was used as a lower layer, and the sheet prepared in Example 2 was used as an upper layer to obtain an agricultural and horticultural sheet, and the results were evaluated (the results are shown in Table 1).

Example 7 Resins were blended at a weight ratio of A = 35, B = 60, and C = 5% by weight, and fiberization was performed using a biodegradable resin composition. 0.3% by weight of lauryl phosphate potassium salt was adhered to the obtained yarn, and 12 threads / 25
mm, and cut to a fiber length of 51 mm.
/ F staples were obtained. This staple was spun into a 48/1 cotton yarn by ordinary worsted spinning. Using this spun yarn, a warp density of 20 yarns / inch and a weft yarn density of 20 yarns /
An inch plain woven fabric was prepared. This fabric was made into a nonwoven fabric sheet by through-air processing. The obtained sheet was used as an agricultural and horticultural sheet in which the medium sheet prepared in Example 5 was disposed in the middle layer and the medium sheet prepared in Example 5 was arranged in the surface layer and the lower layer.
Described).

Example 8 A resin was blended at a weight ratio of A = 35, B = 60, C = 5% by weight, and extrusion was performed to form a film. A hole was made in this film with a needle punching machine to obtain an agricultural and horticultural sheet. A field test was conducted using this,
The disintegration time was measured. (Results are shown in Table 1).

Comparative Example 1 Using a biodegradable fiber using only polycaprolactone, a nonwoven fabric was produced by the above-described nonwoven fabric production method using a hot roll, and processed and evaluated in the same manner as in Example 1 as an agricultural / horticultural sheet. Performed (the results are shown in Table 1).

Comparative Example 2 Resins were blended at a weight ratio of A = 35, B = 0, C = 65% by weight to obtain a biodegradable resin composition. Spinning was performed using this, but the spinnability was extremely poor, and no sample was obtained (the results are shown in Table 1).

Comparative Example 3 Resins were blended at a weight ratio of A = 40, B = 60, C = 0% by weight to obtain a biodegradable resin composition. Spinning was performed using this, but the spinnability was extremely poor, and no sample was obtained (the results are shown in Table 1).

[0042]

[Table 1]

In the embodiment, an example was shown in which only partially ethylene was used as the unsaturated monomer in the partially hydrolyzed copolymer used for the biodegradable fiber. However, this is an example of the unsaturated monomer. The effects of the present invention can be similarly obtained for propylene, isobutylene and styrene.

As is clear from the above results, the time until the sheet collapses can be controlled by changing the amount of the aliphatic polyester added to the agricultural and horticultural sheet of the present invention.

[0045]

The agricultural and horticultural sheet of the present invention has excellent disintegration performance and the disintegration period can be adjusted according to the purpose.
After use, it collapses quickly, the sheet is not required to be collected, and since it is composed of components harmless to agricultural land, there is no risk of causing soil contamination.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location D03D 15/00 D03D 15/00 H D04H 1/42 D04H 1/42 Z 1/54 1/54 JA // D01F 8/00 D01F 8/00

Claims (6)

[Claims] An agricultural and horticultural sheet comprising a fabric obtained by molding and processing a biodegradable resin composition containing the following components (A), (B) and (C), wherein the composition comprises: An agricultural and horticultural sheet, wherein (A) contains 30 to 70% by weight, (B) 25 to 65% by weight, and (C) 5 to 40% by weight. (A) Starch polymer (B) Copolymer obtained by partially hydrolyzing a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group (C) Aliphatic polyester 2. One or both sides of a nonwoven fabric, a knitted fabric or a woven fabric formed of a biodegradable fiber obtained by spinning a biodegradable resin composition containing the following components (A), (B) and (C): And an agricultural and horticultural sheet obtained by laminating a functional sheet, wherein (A) is 30 to 70% by weight in the composition,
(B) is 25 to 65% by weight, and (C) is 5 to 40% by weight.
An agricultural and horticultural sheet characterized by containing by weight. (A) Starch polymer (B) Copolymer obtained by partially hydrolyzing a copolymer obtained by partially hydrolyzing a copolymer of vinyl acetate and an unsaturated monomer having no functional group (C) Aliphatic polyester 3. The agricultural and horticultural sheet according to claim 2, wherein the functional sheet is at least one selected from a fertilizer-containing sheet, a seaweed sheet, an endothermic sheet, a hygroscopic sheet, and an insect-proof and antibacterial sheet. 4. The agricultural and horticultural sheet according to claim 1, wherein the starch-based polymer is a thermoplastic melt obtained by modifying at least one kind of plant starch. 5. The unsaturated monomer having no functional group is at least one unsaturated monomer selected from ethylene, propylene, isobutylene and styrene, and the partially hydrolyzed copolymer has a degree of saponification. 4. The agricultural and horticultural sheet according to claim 2, wherein the amount is 78 to 98%, and the partially hydrolyzed copolymer is contained in an amount of 25 to 65% by weight based on the biodegradable fiber. 5. 6. The agricultural and horticultural sheet according to claim 1, wherein the aliphatic polyester is a biodegradable resin having a melting point of 150 ° C. or less.