JP2001003255A - Water-soluble nonwoven fabric for agricultural chemical packaging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a non-woven fabric for packing an agrochemical, consisting of a PVA-based melt blown water soluble non-woven fabric having an excellent water solubility and suitable barrier property. SOLUTION: This non-woven fabric is a melt blown non-woven fabric consisting of a polyvinyl alcohol having 200-500 viscosity-average molecular weight, 90-99.99 mol% saponification degree, 66-99.9 mol% molar fraction of central hydroxyl group of hydroxyl group triad by the triad expression toward the vinyl alcohol unit and 160-230 deg.C melting point, and containing (B) 0.0003-1 pt.wt. alkali metal ion based on (A) 100 pts.wt. polyvinyl alcohol. The breaking strength of the non-woven fabric after immersing it in water at 20 deg.C for 5 min is <=10 g/5 cm, the mean fiber diameter of the fibers constituting the non- woven fabric is <=20 μm and its degree of air ventilation is <=100 cc/cm2/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonwoven fabric for packaging agricultural chemicals comprising a thermoplastic polyvinyl alcohol-based meltblown nonwoven fabric having a specific composition.

[0002]

2. Description of the Related Art Conventionally, polyvinyl alcohol (hereinafter referred to as P
VA may be abbreviated). Examples of the fibers include: 1) a fiber obtained by wet spinning of a stock solution and a solidification bath, both of which are aqueous; 2) a fiber obtained by dry spinning of a stock solution of water; 3) any of a stock solvent and a solidification bath. Fibers formed by wet spinning (gel spinning) using a solvent system are known.

[0003] These PVA-based water-soluble fibers are used as staples or shortcut fibers in papermaking, dry nonwoven fabrics, spinning, and the like, and as multifilaments in woven fabrics and knitted fabrics. In particular, shortcut fibers soluble in hot water at 80 ° C. to 90 ° C. occupy an important position in the papermaking industry as fibrous binders, and multifilaments are also often used as base fabrics for chemical lace.
In recent years, biodegradable fibers have attracted attention due to environmental problems.

On the other hand, in the nonwoven fabric manufacturing technique, a so-called melt-blown nonwoven fabric manufacturing technique uses a conventional dry nonwoven fabric in which a nonwoven fabric is formed directly from a raw material polymer, and is then formed into fibers and then formed in a separate process. It is known as an extremely rational method for producing a nonwoven fabric as compared with the production technology for wet and nonwoven fabrics. Furthermore, since this melt blown nonwoven fabric is basically manufactured using a melt spinning method, unlike a nonwoven fabric composed of conventional PVA fibers obtained by a wet spinning method using an organic solvent, There is no problem that a trace amount of the organic solvent remains in the nonwoven fabric.

[0005] In a so-called dry nonwoven fabric manufacturing technique in which a fiber is once manufactured and the fiber is carded into a nonwoven fabric, various processes are required in the fiber manufacture and carding for forming a nonwoven web is required. It is essential to attach an oil agent to the fiber surface during the production of the fiber, and the oil agent is usually treated with an aqueous treatment liquid. However,
Water-based treatment liquids cannot be used to produce fibers that exhibit strong affinity for water, such as water solubility, water absorption, and water swelling properties. Equipment measures were necessary. As a result, there has been a great limitation in producing such a nonwoven fabric using fibers as a raw material while ensuring desired quality.

[0006] Attempts to apply such a rational melt-spinning nonwoven fabric manufacturing technique to PVA-based fiber nonwoven fabrics have been conventionally studied in the so-called spunbond method.

For example, as an example of converting PVA into a nonwoven fabric by a direct method, Japanese Patent Application Laid-Open No. 51-112980 discloses an average degree of polymerization of 50 to 300 and a residual acetic acid group of 15 to 80.
Disclosed is a method for producing a polyvinyl alcohol yarn synthetic fiber nonwoven fabric, wherein a filament obtained by melt-extruding mol% of anhydrous polyvinyl alcohol is taken up by a suction jet and sprayed and deposited on a forming surface by a jet stream. Average degree of polymerization of 50 to 300 and residual acetic acid groups of 15
In the case of PVA of up to 80 mol%, a nonwoven fabric cannot be obtained if it is used for an extremely short time. However, during the heating and melting, a deacetic acid reaction occurs and the working environment is poor due to the generated acetic acid gas. In addition, gelation occurs due to cross-linking due to intermolecular deacetic acid, which causes problems such as an increase in melt viscosity, gel mixing into the spun polymer stream, cutting of the polymer stream, and filter clogging. , Not at the level of industrial production.

A melt blown nonwoven fabric made of PVA is disclosed in a paper by Maureen Dever, Ph.D., "Development and Evaluation of Water Soluble Blown Melt Blown".
Non-Woovens "(Development and Evaluation of
Water Soluble Melt Blown Nonwovens), TAPPI P
Although disclosed in Roceedings, Nonwovens Conference, pp 99-110, 1993, in this paper melt blowns are made to ensure good cold water solubility and biodegradability, especially using a PVA resin with a saponification degree of less than 90%. ing.

A paper by AYAKhan et al., "Melt Blown Processing and Characterization of Cellulose Acetate and Polyvinyl Alcohol"
erization of Cellulose Acetate and Polyvinyl A
lcohol), TAPPI Proceedings, Nonwovens Conference, p
p111-113, 1993 discloses a melt blown nonwoven fabric using PVA, but the resin used here is MI = 26-
No. 30 is disclosed, and no specific resin composition is disclosed. Further, JP-A-5-3450
No. 13 discloses PVA which shows water solubility at a temperature of 50 ° C. or more.
A fabric comprising a homopolymer is disclosed, and a melt blown nonwoven fabric is disclosed as an example of the fabric.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a nonwoven fabric for agricultural chemical packaging comprising a polyvinyl alcohol meltblown nonwoven fabric having excellent water solubility and moderate barrier properties.

[0011]

That is, according to the present invention, the viscosity average degree of polymerization is from 200 to 500 and the degree of saponification is from 90 to 99.
99 mol%, the molar fraction of the central hydroxyl group of three hydroxyl groups in the triad notation with respect to the vinyl alcohol unit is 66 to 99.9 mol%, and the melting point is 160 ° C. to 23.
A polyvinyl alcohol (A) at 0 ° C.,
(A) 100 parts by weight of alkali metal ion (B)
Is a melt-blown nonwoven fabric made of polyvinyl alcohol containing 0.0003 to 1 part by weight, and the nonwoven fabric has a breaking strength of 10 after immersion in water at 20 ° C. for 5 minutes.
g / 5 cm or less is a water-soluble nonwoven fabric for agricultural chemical packaging,
Preferably, the average fiber diameter of the fibers constituting the nonwoven fabric is 20μ.
m or less and an air permeability of 100 cc / cm ² / sec or less.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyvinyl alcohol in the polyvinyl alcohol-based melt-blown nonwoven fabric of the present invention includes a homopolymer of polyvinyl alcohol and a modified polyvinyl alcohol having a functional group introduced by copolymerization, terminal modification and post-reaction.

The viscosity-average degree of polymerization (hereinafter, abbreviated as degree of polymerization) of PVA used in the present invention is from 200 to 500, preferably from 230 to 470, particularly preferably from 250 to 450. When the degree of polymerization exceeds 500, the melt viscosity is high, so that the average fiber diameter of the melt blown nonwoven fabric becomes large, and fibers in which a partially coiled or ball-like mass is mixed are mixed and roughened. The resulting nonwoven fabric becomes soft to the touch, and the characteristics of the meltblown nonwoven fabric cannot be utilized. If the degree of polymerization is further increased, the polymer cannot be discharged from the nozzle.

The degree of polymerization (P) of PVA is determined according to JIS-K
It is measured according to 6726. That is, PVA is re-soaped
Intrinsic viscosity measured in water at 30 ℃ after purification
Is obtained from [η] (dl / g) by the following equation.
You. P = ([η] × 1000 / 8.29)^{(1 / 0.62)}  When the degree of polymerization is in the above range, the object of the present invention is more suitable
Can be reached.

The degree of saponification of the PVA used in the present invention is 90
９９99.99 mol%, 92-99.9
8 mol% is preferable, 93 to 99.97 mol% is more preferable, and 94 to 99.96 mol% is particularly preferable. When the saponification degree is less than 90 mol%, the thermal stability of PVA is poor, and not only melt blown spinning cannot be performed satisfactorily due to thermal decomposition or gelation, but also an aqueous solution of PVA depending on the type of copolymerizable monomer described below. In some cases, the water-soluble non-woven fabric intended in the present invention cannot be obtained. On the other hand, PVA having a degree of saponification of more than 99.99 mol% cannot be produced stably and fiberization cannot be stabilized.

In the present invention, the central hydroxyl group of the triad of the triad is defined as d6-DMS of PVA.
500 MHz proton NMR (JEOLG
X-500) Peak (I) that reflects the triad tacticity of hydroxyl protons measured at 65 ° C.
Means Peak (I) is an isotacticity chain (4.54 pp) of the hydroxyl group of PVA expressed in triad.
m), the sum of the heterotacticity chain (4.36 ppm) and the syndiotacticity chain (4.13 ppm), and the peak (II) derived from the hydroxyl group in all vinyl alcohol units has a chemical shift of 4.0.
Since it appears in the region of 5 ppm to 4.70 ppm,
The molar fraction of the center hydroxyl group of the three-chain hydroxyl group by the triad display with respect to the vinyl alcohol unit of the present invention is:
It is represented by 100 × (I) / (II).

In the present invention, by controlling the amount of the central hydroxyl group of the three hydroxyl groups required above, various physical properties relating to water such as water solubility, hygroscopicity and water resistance of PVA, strength, etc. can be obtained.
We have found that various properties related to fiber such as elongation and elastic modulus, and various properties related to melt molding such as melting point, melt viscosity and melt viscosity can be controlled. This is presumably because the central hydroxyl group of the triad of triads is rich in crystallinity, thereby exhibiting the characteristics of PVA.

In the nonwoven fabric of the present invention, the content of the central hydroxyl group of three hydroxyl groups by the triad display of PVA is 6
6 to 99.9 mol%, preferably 70 to 99 mol%, more preferably 74 to 97 mol%, further preferably 75 to 96 mol%, and particularly preferably 76 to 95 mol%. When the content of the central hydroxyl group of three hydroxyl groups in the triad display of PVA is less than 66 mol%, the crystallinity of the polymer is reduced, the spinnability at the time of melt spinning is poor, and the melt blown nonwoven fabric aimed at by the present invention is not obtained. I am not satisfied. In addition, a water-disintegrable nonwoven fabric may not be obtained. P
When the content of the central hydroxyl group of three hydroxyl groups in the triad display of VA is more than 99.9 mol%, the melting point of the polymer must be increased because the melting point of the polymer is high. Poor thermal stability,
Troubles such as decomposition, gelation and coloring occur.

The melting point of PVA used in the present invention is 160
To 230 ° C, preferably 170 to 227 ° C, 17
5 to 224 ° C is more preferable, and 180 to 220 ° C is particularly preferable. If the melting point is lower than 160 ° C., the crystallinity of the PVA is reduced, so that fibers having sufficient strength cannot be obtained. Are mixed together, resulting in a web that cannot maintain the performance as a so-called melt blown nonwoven fabric, and furthermore, it may not be possible to form a web.
On the other hand, if the melting point exceeds 230 ° C., the blown temperature rises, and the blown temperature approaches the decomposition temperature of PVA.
VA meltblown nonwoven fabric cannot be manufactured stably.

The melting point of PVA is raised to 250 ° C. at a rate of 10 ° C./min in nitrogen, cooled to room temperature, and then raised again to 250 ° C. at a rate of 10 ° C./min in nitrogen using DSC. Means the temperature at the peak top of the endothermic peak indicating the melting point of PVA in this case.

The PVA used in the present invention is obtained by saponifying a vinyl ester unit of a vinyl ester polymer. Vinyl compound monomers for introducing vinyl ester units into the polymer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, and pivalin Examples thereof include vinyl acid and vinyl versatate. Among them, vinyl acetate is preferable from the viewpoint of obtaining PVA.

The PVA constituting the nonwoven fabric of the present invention preferably contains a monomer unit other than a vinyl alcohol unit and a vinyl ester unit. Examples of such a unit include α-olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, n-propyl acrylate, and i-acrylate. Acrylates such as -propyl, methacrylic acid and salts thereof, methyl methacrylate, ethyl methacrylate, methacrylic acid n
-Propyl, methacrylic acid esters such as i-propyl methacrylate, acrylamide, N-methyl methacrylamide, methacrylamide derivatives such as n-ethyl methacrylamide, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, vinyl ethers such as n-butyl vinyl ether, ethylene glycol vinyl ether, 1,3-
Propanediol vinyl ether, hydroxy group-containing vinyl ethers such as 1,4-butanediol vinyl ether, allyl acetate, propyl allyl ether,
Allyl ethers such as butyl allyl ether and hexyl allyl ether, monomers having an oxyalkylene group,
Vinylsilanes such as vinyltrimethoxysilane, isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decene-1 -All 3-methyl-
A carboxyl group derived from hydroxy group-containing α-olefins such as 3-buten-1-ol, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride or itaconic anhydride; Monomer having a sulfonic acid group derived from ethylenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, etc .; vinyloxyethyltrimethylammonium chloride, vinyloxy Methyl diethylamine, N-acrylamidomethyltrimethylammonium chloride, N-
Monomers having a cationic group derived from acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine and the like can be mentioned. The content of these monomers is preferably 25 mol% or less.

Among these monomers, α-olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i -Propyl vinyl ether, vinyl ethers such as n-butyl vinyl ether, hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether, allyl acetate, propyl allyl ether, butyl allyl ether,
Allyl ethers such as hexyl allyl ether, monomers having an oxyalkylene group, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, Monomers derived from hydroxy group-containing α-olefins such as 9-decene-1-ol and 3-methyl-3-buten-1-ol are preferred.

Among them, ethylene, propylene, and ethylene are preferred from the viewpoint of water disintegration showing excellent affinity for water such as copolymerizability, spinnability at the time of blown, water solubility of water, water absorption, and water swellability. Α-olefins having 4 or less carbon atoms, such as butene and isobutene, and vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether are more preferable. Units derived from α-olefins and / or vinyl ethers having 4 or less carbon atoms are represented by P
Preferably, 0.1 to 25 mol% is present in VA, more preferably 0.2 to 15 mol%, and 0.3 to 13 mol%.
Molar% is particularly preferred. Furthermore, when the α-olefin is ethylene, the spinnability at the time of blown becomes good,
Since blown fibers having an average fiber diameter of 20 μm or less are stably formed, it is particularly preferable to use modified PVA in which ethylene units are introduced in an amount of 3 to 20 mol%, more preferably 6 to 13 mol%.

The polymerization method of PVA used in the present invention includes solution polymerization, bulk polymerization, pearl polymerization, emulsion polymerization and the like. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is performed without a solvent or in a solvent such as an alcohol is usually employed. Examples of the alcohol used as a solvent during the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. As the initiator used for the copolymerization, α, α ′
Azo initiators or peroxide initiators such as -azobisisobutyronitrile, 2,2'-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, n-propylperoxydicarbonate, etc. Known initiators. The polymerization temperature is not particularly limited,
A range of 0 ° C to 200 ° C is appropriate.

The content of the alkali metal ion (B) in the PVA used in the present invention is 0.0003 to 1 part by weight with respect to 100 parts by weight of the PVA (A).
03-0.8 parts by weight, preferably 0.0005-0.6 parts by weight
Part by weight is more preferable, and 0.0005 to 0.5 part by weight is particularly preferable. Alkali metal ion content of 0.0
When the amount is less than 003 parts by weight, not only is it easy to gel during blown, it is difficult to form a fiber, but also sufficient water solubility is not obtained and undissolved matter may remain. On the other hand, when the content of the alkali metal ion is more than 1 part by weight, decomposition and gelation at the time of blown are remarkable, and the fiber cannot be formed. Examples of the alkali metal ion include a potassium ion and a sodium ion.

In the present invention, the method of adding a specific amount of alkali metal ion (B) to PVA is not particularly limited, and a method of adding a compound containing an alkali metal ion after once obtaining PVA, When saponifying the coalesced solvent in a solvent, the use of an alkaline substance containing an alkali ion as a saponification catalyst can reduce PV
A method of mixing alkali metal ions in A and washing the PVA obtained by saponification with a washing liquid to control the alkali metal ions contained in PVA can be mentioned, but the latter is more preferable. The content of the alkali metal ion can be determined by an atomic absorption method.

As the alkaline substance used as the saponification catalyst, potassium hydroxide or sodium hydroxide can be mentioned. The molar ratio of the alkaline substance used for the saponification catalyst is
0.004-0.5 is preferable with respect to a vinyl acetate unit, and 0.005-0.05 is especially preferable. The saponification catalyst may be added all at once at the beginning of the saponification reaction, or may be additionally added during the saponification reaction. As the solvent for the saponification reaction, methanol, methyl acetate, dimethyl sulfoxide,
Dimethylformamide and the like. Among these solvents, methanol is preferable, and the water content is 0.001 to 0.001.
Methanol controlled at 1% by weight is more preferable, methanol controlled at a water content of 0.003 to 0.9% by weight is more preferable, and methanol controlled at a water content of 0.005 to 0.8% by weight is particularly preferable. . Examples of the washing liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, and water, and among them, methanol, methyl acetate, and water alone or a mixed liquid are more preferable. The amount of the washing liquid is set so as to satisfy the content ratio of the alkali metal ion (B), but usually 300 to 5,000 parts by weight based on 100 parts by weight of PVA. The washing temperature is preferably from 5 to 80 ° C, and from 20 to 80 ° C.
70 ° C. is more preferred. Washing time is 20 minutes to 1
0 hours is preferable, and 1 hour to 6 hours is more preferable.

Furthermore, the PVA used in the present invention includes:
A plasticizer for lowering the melt viscosity or imparting flexibility to the nonwoven fabric may be added. The plasticizer is not particularly limited as long as it can reduce the glass transition point and melt viscosity of PVA. Examples of the plasticizer include water, ethylene glycol and its oligomers, polyethylene glycol, propylene glycol, and its oligomers, and polyglycerin. Glycerin, glycerin derivatives such as ethylene oxide and propylene oxide, sorbitol, pentaerythritol and the like. Among them, polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol, sorbitol, and pentaerythrol and derivatives thereof are preferably used. The amount of the plasticizer is not limited, but it is preferable to add the plasticizer in the range of 0.01 to 10 parts by weight based on 100 parts by weight of PVA.

In addition, stabilizers such as copper compounds, coloring agents, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, and the like, as long as the objects and effects of the present invention are not impaired.
Plasticizers, lubricants and crystallization rate retarders can be added during the polymerization reaction or in a subsequent step. In particular, when organic stabilizers such as hindered phenol, copper halides such as copper iodide, and alkali metal halides such as potassium iodide are added as heat stabilizers, the melt retention stability during fiberization is improved. Is preferred.

Further, if necessary, the average particle size is 500
Fine particles having a size of not more than nm can be added in an amount of 0.1 to 5% by weight during the polymerization reaction or in a subsequent step. The type of the fine particles is not particularly limited. For example, silica gel (colloidal silica), dry silica, dry silica containing aluminum oxide, dry silica having an alkyl group on the particle surface and silanol groups blocked on the particle surface, Inert fine particles such as alumina sol (colloidal alumina), titanium oxide, calcium carbonate and its sol (colloidal calcium carbonate); and internally precipitated fine particles obtained by reacting and depositing a phosphorus compound and a metal compound in a PVA polymerization reaction system. it can. Particularly, silica having an average particle diameter of 15 to 70 nm is preferable, and the melt blown spinnability is improved.

The production of the melt blown nonwoven fabric comprising the polyvinyl alcohol of the present invention is described in, for example, Industrial and Engineering Chemistry, 48
Vol. 8, No. 134 (p1342-p1346), 1956
Can be manufactured using a known melt blown apparatus. That is, the PVA pellets are melt-kneaded by a melt extruder, the melted polymer is weighed by a gear pump, guided to a melt blown spinning nozzle, discharged, blown off by a heated air stream, and spun. To form a non-woven fabric and winding it up. Further, by blowing cold air of about 40 ° C. or less into the melt blown fiber flow just below the nozzle, the degree of fiber adhesion in the nonwoven fabric can be minimized, and the resulting nonwoven fabric can be made more flexible.

However, as a condition for forming a melt blown nonwoven fabric in the present invention, it is important to perform melt blown spinning at a blown temperature of (Tm + 10 ° C.) to (Tm + 80 ° C.) with respect to the melting point Tm of the polymer. If the blown temperature is lower than (Tm + 10 ° C.), the melt viscosity of the polymer is too high, and the resin cannot be thinned by high-speed blown air, resulting in a very coarse nonwoven fabric. Also, (Tm + 80
C.), thermal decomposition of PVA occurs and stable spinning cannot be performed.

The melting point Tm of PVA is the peak temperature of the main endothermic peak observed by a differential scanning calorimeter (DSC: for example, TA3000 from Mettler) as described above.

In the melt blown nonwoven fabric of the present invention, if necessary, a part or all of the fibers may be thermocompression-bonded to improve the adhesive force between the fibers and improve the strength of the nonwoven fabric. Since the fibers constituting the melt blown nonwoven fabric of the present invention have a low degree of adhesion between the fibers when the web is formed, the fibers may be broken in a form in which the fibers of the web are pulled out. Therefore, it is better to improve the web strength and to improve the practicality by thermocompression bonding and fixing the fibers partially or over the entire surface by, for example, hot embossing or a heat calender. From the viewpoint of preventing powder leakage of pesticides, heat calendering is more preferable. The temperature, pressure, processing speed, embossing roll pattern, etc. of the heating roll in the thermocompression bonding can be appropriately selected depending on the purpose. The PVA-based long fiber constituting the nonwoven fabric of the present invention is active against water, and its apparent melting point decreases in the presence of water.
It is possible to reduce the temperature of the heating roll.

The thermoplastic PVA-based meltblown nonwoven fabric of the present invention thus obtained preferably has an average fiber diameter of 20 μm or less, preferably 10 μm or less, from the viewpoint of preventing the leakage of pesticide powder. More preferred. The air permeability of the nonwoven fabric per unit area is 100 cc /
It is preferably at most cm ² / sec, more preferably at most 20 cc, particularly preferably at most 5 cc. If the average fiber diameter exceeds 20 μm or the air permeability exceeds 100 cc / cm ² / sec, the barrier properties are poor, and powder leakage of the pesticide tends to occur. Further, the nonwoven fabric of the present invention has water solubility,
Water-absorbing, water-disintegrating properties showing strong affinity for water such as water swelling properties, and good non-woven fabric showing good water-disintegrating properties, especially water-solubility, even in cold water at 5 ° C. ° C
Treatment with water in the normal environmental temperature range of ３０30 ° C. is possible. In this case, it is necessary to keep the above-mentioned embossing temperature or calendar temperature below a low temperature (about 80 ° C.).

Here, the water-disintegrability of the nonwoven fabric means that the nonwoven fabric does not remain in the original sheet form.
Typically, the non-woven fabric is dissolved by water, the fibers constituting the non-woven fabric are disconnected from each other, and the shape of the sheet is not maintained.In some cases, due to water absorption, swelling, etc., shrinkage, bending, distortion such as wrinkles Indicates that it will be clumped.

The melt-blown non-woven fabric thus obtained is a non-woven fabric having water disintegration properties as it is,
When it is necessary to exhibit water disintegration at a higher temperature, the nonwoven fabric can be adjusted by heat treatment. This is because the heat treatment promotes crystallization of the resin forming the fibers. The heat treatment itself may be performed during the melt blown nonwoven fabric manufacturing process, or may be performed by a method of once winding and then performing a heat treatment again.

The method of heat treatment may be any method other than directly exposing the nonwoven fabric to water, such as a water bath.
Although it can be performed by a heat roller or the like, a method of performing treatment using a heat roller which is industrially easy to perform continuous processing is preferable. When this heat roller is used, a method is used in which the nonwoven fabric touches the heat roller. This heat treatment
Heat treatment may be applied to only one side of the nonwoven fabric, or both sides may be treated. If necessary, not only heat but also pressure may be applied simultaneously. A calendar process or an emboss process may be performed according to the purpose. The dissolving temperature of the nonwoven fabric in water is determined by the boiling temperature of the nonwoven fabric dissolved in cold water, depending on the blown conditions such as the blown temperature and the amount of blown air, and the heat history such as the heat treatment temperature or heat treatment time after the nonwoven fabric, in addition to the specifications of the raw material polymer. Even nonwoven fabrics that dissolve in water can be freely changed.

The nonwoven fabric for packaging agricultural chemicals of the present invention comprises
Breaking strength after immersion in water at 0 ° C for 5 minutes is 10g / 5cm
It is a nonwoven fabric of preferably 5 g / 5 cm or less, more preferably 1 g / 5 cm or less. If the breaking strength after 5 minutes in water at 20 ° C. is greater than 10 g / cm, when the pesticide packaged with the water-soluble nonwoven fabric is thrown into a paddy field or the like, the pesticide is difficult to come out of the bag and spread. Since this breaking strength varies depending on the type of polymer, nonwoven fabric manufacturing conditions, heat treatment conditions, and the like, it is necessary to reduce the breaking strength to 5 g · cm or less by appropriately combining them.

The fibers constituting the PVA meltblown nonwoven fabric of the present invention are biodegradable, and are decomposed into water and carbon dioxide when treated with activated sludge or buried in soil. When the fibers are continuously treated with activated sludge, they are almost completely decomposed in about two days to one month. From the viewpoint of biodegradability, the saponification degree of the fiber is preferably 90 to 99.99 mol%,
-99.98 mol% is more preferable, and 93-99.97.
Molar% is particularly preferred. Further, the content of 1,2-glycol bond in the modified PVA constituting the nonwoven fabric is from 1.2 to 1.2.
2.0 mol% is preferable, 1.25 to 1.95 mol% is more preferable, and 1.3 to 1.9 mol% is particularly preferable.
When the content of the 1,2-glycol bond in the PVA is 2.0 mol% or more, the thermal stability of the PVA deteriorates, and the melt blown spinnability may decrease. 1, in PVA
The 2-glycol bond content can be determined from the NMR peak. After saponification to a degree of saponification of 99.9 mol% or more, the sample was thoroughly washed with methanol, and then dried under reduced pressure at 90 ° C. for 2 days. PVA was dissolved in d6-DMSO, and a few drops of trifluoroacetic acid were added. Using proton NMR of 500 MHz (JEOL GX-500), 80 ° C.
Measure with The peak derived from the methine group of the vinyl alcohol unit is 3.2 to 4.0 ppm (integral value A), and the peak derived from one methine group of the 1,2-glycol bond is 3.25.
ppm (integral value B), and the 1,2-glycol bond content can be calculated by the following equation. Here, Δ represents the amount of modification (mol%). 1,2-glycol bond content (mol%) = B (100
−Δ) / A

The PVA meltblown nonwoven fabric of the present invention can be imparted with water solubility or disintegration depending on the use by selecting PVA and setting conditions during the production of the nonwoven fabric. The PVA meltblown nonwoven fabric is used alone or laminated with another nonwoven fabric, woven or knitted fabric, film, or the like for the purpose of reinforcement or the like, and is suitably used for packaging agricultural chemicals.

[0043]

EXAMPLES Next, the present invention will be described specifically with reference to Examples.
The present invention is not limited to these examples. The parts and percentages in the examples relate to weight unless otherwise specified.

The method for analyzing the PVA and the method for measuring the ratio of the three-chain hydroxyl groups and the melting point of the PVA by the triad display of the PVA are as described above.

[Breaking Strength] The breaking strength in water of the PVA-based melt blown nonwoven fabric of the present invention is 5 cm in width and 10 cm in length.
cm of a nonwoven fabric sample, attached to a wet tensile tester (manufactured by Shimadzu Corporation), and adjusted to a temperature of 20 ° C.
Add 00 cc of distilled water and leave for 5 minutes. afterwards,
A tensile test was performed to determine the breaking strength.

[Measurement of air permeability] JIS L1096
The measurement was performed with a Frazier tester in accordance with the method A of “General fabric test method”.

[Measurement of Average Fiber Diameter] Using a scanning electron microscope, a photograph of the surface of the nonwoven fabric was magnified 1000 times, two diagonal lines were drawn on the photograph, and the thickness of the fiber crossing the diagonal line was drawn. A value obtained by converting the magnification into a magnification was used. And the average value of 100 of those fibers was used as the average fiber diameter. However, when the diameter of one fiber could not be measured because the corresponding fiber was unclear or a plurality of fibers were overlapped, it was excluded from the measurement target.

Example 1 29.0 kV of vinyl acetate was placed in a 100 L pressurized reaction tank equipped with a stirrer, a nitrogen inlet, an ethylene inlet and an initiator inlet.
g and 31.0 kg of methanol were charged, the temperature was raised to 60 ° C., and the system was replaced with nitrogen by bubbling nitrogen for 30 minutes. Then, ethylene was introduced and charged so that the reaction tank pressure became 5.9 kg / cm ² . 2,2 'as initiator
-Azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol at a concentration of 2.8.
The g / L solution was adjusted, and nitrogen replacement was performed by bubbling with nitrogen gas. After adjusting the internal temperature of the polymerization tank to 60 ° C., 170 ml of the initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to increase the reaction tank pressure to 5.9 k.
g / cm ² , the polymerization temperature was maintained at 60 ° C., and AMV was continuously added at 610 ml / hr using the above initiator solution to carry out polymerization. After 10 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. After the reactor was released and ethylene was removed, nitrogen gas was bubbled through to completely remove ethylene. Then, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. Methanol was added to the obtained polyvinyl acetate solution to adjust the concentration to 50% by adding 200 g of methanol solution of polyvinyl acetate (molar ratio (MR) to vinyl acetate unit in solution: 0.10). Alkaline solution (N
(10% methanol solution of aOH) was added for saponification. Approximately 2 minutes after the addition of the alkali, the gelled system was pulverized with a pulverizer, left at 60 ° C. for 1 hour to allow saponification to proceed, and then 1000 g of methyl acetate was added to neutralize the remaining alkali. did. After confirming the completion of neutralization using a phenolphthalein indicator, the white solid PV obtained by filtration was obtained.
A, 1000 g of methanol was added to A, and it was left and washed at room temperature for 3 hours. After repeating the above washing operation three times, the PVA obtained by centrifugal dewatering was left in a dryer at 70 ° C. for 2 days to obtain dry PVA.

The resulting ethylene-modified PVA has a degree of saponification of 9
It was 8.4 mol%. After the modified PVA was ashed, the content of sodium measured by an atomic absorption spectrophotometer using a substance dissolved in an acid was 0.03 parts by weight based on 100 parts by weight of the modified PVA. Further, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after polymerization was added to n-hexane, and the precipitated polyvinyl acetate was collected.Then, the polyvinyl acetate was dissolved in acetone. After reprecipitation purification by adding to n-hexane again and precipitating three times, drying under reduced pressure at 80 ° C. for 3 days was performed to obtain purified polyvinyl acetate. The polyvinyl acetate was dissolved in d6-DMSO, and 500 MHz proton NM was added.
The content of ethylene was 10 mol% as measured at 80 ° C. using an R (JEOL GX-500) apparatus. After saponifying the above methanol solution of polyvinyl acetate at an alkali molar ratio of 0.5, the pulverized product was treated at 60 ° C for 5 hours.
After allowing the saponification to proceed for a period of time, methanol soxhlet was carried out for 3 days, and then dried under reduced pressure at 80 ° C. for 3 days to obtain purified ethylene-modified PVA. The PVA
The average degree of polymerization was 330 according to a standard method of JIS K6726. The amount of 1,2-glycol bond and the content of hydroxyl group of three hydroxyl groups of the purified PVA were determined by 500 MHz proton NMR (JEOL GX-50).
0) It was 1.50 mol% and 83 mol%, respectively, as determined from the measurement by the apparatus as described above. Further, a 5% aqueous solution of the purified modified PVA was prepared to prepare a cast film having a thickness of 10 μm. After the film was dried under reduced pressure at 80 ° C. for 1 day, the film was dried using DSC (Mettler, TA3000) according to the method described above.
The melting point of VA was 206 ° C. (Table 1)

[0050]

[Table 1]

The PVA obtained above was melt-kneaded at 250 ° C. using a melt extruder, and the melted polymer stream was guided to a melt blow die head, weighed with a gear pump, and holes having a diameter of 0.3 mmφ were formed at a pitch of 0.75 mm. The fibers were discharged from the melt blown nozzles arranged in a line, and at the same time, hot air of 250 ° C. was sprayed on the resin, and the discharged fibers were collected on a molding conveyor to obtain a melt blown nonwoven fabric having a basis weight of 50 g / m ² . At this time, the single-hole discharge amount of the resin was 0.2 g / min / hole, the hot air flow was 0.15 Nm ³ / min / cm width,
The distance between the nozzle and the collection conveyor was 15 cm. Also, at this time, an air flow of 15 ° C. was blown into the melt blown fiber stream at a flow rate of 1 m ³ / min / cm width using equipment provided with a secondary air blowing device immediately below the nozzle of the melt blown device.

The obtained melt-blown nonwoven fabric became a nonwoven fabric having a fiber diameter of 9.6 μm and an air permeability of 140 cc / cm ² / sec. When it was put into cold water at 5 ° C., it dissolved without remaining the original nonwoven fabric form. Similarly, even when poured into warm water of 50 ° C., the nonwoven fabric did not remain in the original nonwoven fabric form but dissolved. In addition, the evaluation results of the blown state and the state of the obtained nonwoven fabric are collectively shown in Table 2. The meanings of the symbols in the table are as follows. ：: extremely good ○: good △: slightly difficult ×: poor In addition, the air permeability and breaking strength of this nonwoven fabric are shown in Table 3.
It described in. Further, a bag of 15 × 15 cm was prepared from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) was put therein and stored for 3 months in an environment of 40 ° C. × 65% RH.
Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 3.

[0053]

[Table 2]

[0054]

[Table 3]

Examples 2 to 14 PVA melt blown nonwoven fabrics were obtained under the same conditions as in Example 1 except that the PVA shown in Table 1 was used and the blown conditions shown in Table 2 were employed. The evaluation results such as the blown state and the state of the obtained nonwoven fabric are collectively shown in Table 2. Table 3 shows the air permeability and breaking strength of the nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is used.
And stored for 3 months in an environment of 40 ° C. × 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 3.

Comparative Examples 1 to 5 PVA melt blown nonwoven fabrics were obtained under the same conditions as in Example 1 except that the PVA shown in Table 1 was used and the blown temperature shown in Table 2 was used. Table 2 shows the blown state, the state of the obtained nonwoven fabric, the water disintegration property, and the overall evaluation results. When PVA shown in Comparative Example 1 was used, the melt viscosity was too high, so that stable ejection from a spinning hole could not be performed, and a nonwoven web could not be formed. Increasing the blown temperature to 270 ° C. reduced the apparent melt viscosity but caused degradation and gelation, further exacerbating the situation. In the case where the PVA of Comparative Example 2 was used, the melt viscosity was too low, so that the drip-shaped discharge was mixed and stable fiber formation could not be performed, and the nonwoven web could not be formed. In Comparative Example 3, yarn breakage occurred frequently due to the generation of gas containing acetic acid due to the thermal decomposition of PVA and gelation, and countless granular resins were scattered all over the surface, so that a so-called nonwoven web was not formed. In Comparative Example 4, at a blown temperature of 260 ° C., the melt viscosity was too high because it was close to the polymer melting point. So 2
Increasing the blown temperature to 70 ° C. reduced the apparent melt viscosity, but caused decomposition and gelation, further exacerbating the situation. In Comparative Example 5, it was presumed that the crystallinity of PVA was reduced, but the formed nonwoven fabric was stuck to the collector net and could not be wound.

Comparative Example 6 When manufacturing the PVA used in Example 1, the same methanol washing as in Example 1 was performed four times, and then washing was performed three times with a mixed solution of methanol / water = 90/10. PV with the sodium ion content of 0.0001 parts by weight
Using A, spinning was attempted in the same manner as in Example 1. As a result, countless granular resins were scattered on one side, and did not reach the point where the nonwoven fabric was wound. It is considered that the increase in the melt viscosity was due to the generation of a gel-like substance in the melt system.

Comparative Example 7 In the same manner as in Example 1, except that the PVA used in Example 1 was produced without using methanol washing, PVA having a sodium ion content of 1.4 parts by weight was used. But it could not be stably blown due to thermal decomposition.

Comparative Examples 8 to 12 In place of the PVA used in Example 1, PVA shown in Table 1 was used, and PVA was made of ultrafine fibers under the same conditions as in Example 1 except for the blown temperature shown in Table 2. A non-woven fabric was used.
Table 2 shows the spinnability and the evaluation results of the obtained nonwoven fabric.
When the PVA shown in Comparative Example 8 was used, the PVA
It was gelled and had poor blown spinnability, and did not reach the point where the nonwoven fabric was wound. In Comparative Example 9, the blown temperature 210
At 0 ° C, spinnability was poor and fiberization was not possible, and nonwoven web formation was not possible. By setting the blown temperature to 240 ° C., the apparent melt viscosity decreases, but decomposition and gelation occur, yarn breakage occurs frequently, and countless granular resins are scattered all over the surface,
A non-woven web could not be formed. In Comparative Example 10 and Comparative Example 11, the spinnability was good and the state of the nonwoven fabric was good, but the water disintegrability, which is the object of the present invention, was insufficient and was unsuitable. Table 3 shows the physical properties of the nonwoven fabric. In Comparative Example 12, PVA having a low degree of polymerization and a low degree of saponification similar to those conventionally studied was used. Spinning temperature 230 ° C
However, pyrolysis and gelation occurred from the beginning, and did not lead to fiberization.

Examples 15 to 18 The PVA meltblown nonwoven fabric obtained in Example 1 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 19 to 22 The PVA meltblown nonwoven fabric obtained in Example 2 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion with a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 23 to 26 The PVA melt blown nonwoven fabric obtained in Example 3 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion with a compression area ratio of 20% and a flat metal roll, and embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 27 to 30 The PVA meltblown nonwoven fabric obtained in Example 4 was embossed by thermocompression bonding between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 31 to 34 The PVA meltblown nonwoven fabric obtained in Example 5 was embossed by thermocompression between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 35 to 38 The PVA melt-blown nonwoven fabric obtained in Example 6 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, followed by embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 39-42 The PVA meltblown nonwoven fabric obtained in Example 7 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, and embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 43 to 46 The PVA meltblown nonwoven fabric obtained in Example 8 was embossed by thermocompression bonding between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 47 to 50 The PVA meltblown nonwoven fabric obtained in Example 9 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, followed by embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and the flat roll at this time are as shown in Table 4, and the linear pressure was 35.
kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric. In addition, a bag of 15 × 15 cm is made from this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. × 6.
It was stored for 3 months in an environment of 5% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 4.

Examples 51 to 54 The PVA meltblown nonwoven fabric obtained in Example 10 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a crimping area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and flat roll at this time are as shown in Table 4, and the linear pressure was 3
5 kg / cmL, speed 5 m / min. Table 4 shows the air permeability and breaking strength of this nonwoven fabric.
In addition, a bag of 15 × 15 cm is made of this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. ×
Stored for 3 months in an environment of 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured.
The results are shown in Table 4.

[0070]

[Table 4]

Examples 55 to 58 The PVA meltblown nonwoven fabric obtained in Example 11 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, and embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and flat roll at this time are as shown in Table 5, and the linear pressure was 3
5 kg / cmL, speed 5 m / min. Table 5 shows the air permeability and breaking strength of this nonwoven fabric.
In addition, a bag of 15 × 15 cm is made of this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. ×
Stored for 3 months in an environment of 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured.
The results are shown in Table 5.

Examples 59-62 The PVA meltblown nonwoven fabric obtained in Example 12 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, and embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and flat roll at this time are as shown in Table 5, and the linear pressure was 3
5 kg / cmL, speed 5 m / min. Table 5 shows the air permeability and breaking strength of this nonwoven fabric.
In addition, a bag of 15 × 15 cm is made of this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. ×
Stored for 3 months in an environment of 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured.
The results are shown in Table 5.

Examples 63 to 66 The PVA meltblown nonwoven fabric obtained in Example 13 was subjected to thermocompression embossing between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll, and embossing. A non-woven fabric was obtained. The surface temperatures of the engraving roll and flat roll at this time are as shown in Table 5, and the linear pressure was 3
5 kg / cmL, speed 5 m / min. Table 5 shows the air permeability and breaking strength of this nonwoven fabric.
In addition, a bag of 15 × 15 cm is made of this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. ×
Stored for 3 months in an environment of 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured.
The results are shown in Table 5.

Examples 67 to 70 The PVA melt-blown nonwoven fabric obtained in Example 14 was embossed by thermocompression bonding between a metal engraving roll having a round convex portion having a compression area ratio of 20% and a flat metal roll. A non-woven fabric was obtained. The surface temperatures of the engraving roll and flat roll at this time are as shown in Table 5, and the linear pressure was 3
5 kg / cmL, speed 5 m / min. Table 5 shows the air permeability and breaking strength of this nonwoven fabric.
In addition, a bag of 15 × 15 cm is made of this nonwoven fabric, and 20 g of a commercially available pesticide (Lidomill MZ wettable powder) is put in the bag at 40 ° C. ×
Stored for 3 months in an environment of 65% RH. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured.
The results are shown in Table 5.

Comparative Examples 13 and 14 The nonwoven fabric of Example 1 was embossed in the same manner as in Example 15 except that the surface temperature of the roll was changed as shown in Table 5. Table 5 shows the roll temperature, the air permeability and the breaking strength of the obtained nonwoven fabric.

[0076]

[Table 5]

Examples 71 to 74 The PVA melt blown nonwoven fabric obtained in Example 1 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at the temperatures shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 75 to 78 The PVA meltblown nonwoven fabric obtained in Example 2 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 79 to 82 The PVA meltblown nonwoven fabric obtained in Example 3 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 83 to 86 The PVA meltblown nonwoven fabric obtained in Example 4 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 87 to 90 The PVA meltblown nonwoven fabric obtained in Example 5 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 91 to 94 The PVA meltblown nonwoven fabric obtained in Example 6 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 95 to 98 The PVA meltblown nonwoven fabric obtained in Example 7 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 99 to 102 The PVA meltblown nonwoven fabric obtained in Example 8 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 103 to 106 The PVA meltblown nonwoven fabric obtained in Example 9 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, 15
A bag having a size of 15 cm was prepared, and 20 g of a commercially available pesticide (Lidomil MZ wettable powder) was put in the bag and stored for 3 months in an environment of 40 ° C and 65% RH. After three months, remove the pesticides from the nonwoven fabric,
The breaking strength in water was measured. The results are shown in Table 6.

Examples 107 to 110 The PVA meltblown nonwoven fabric obtained in Example 10 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at the temperatures shown in Table 6. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 6 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, this non-woven fabric
Create a bag of 5 x 15 cm and use a commercially available pesticide (Lidomill MZ)
Wettable powder) 20g and put in an environment of 40 ° C x 65% RH
Stored for months. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 6.

[0087]

[Table 6]

Examples 111 to 114 The PVA meltblown nonwoven fabric obtained in Example 11 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 7. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 7 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, this non-woven fabric
Create a bag of 5 x 15 cm and use a commercially available pesticide (Lidomill MZ)
Wettable powder) 20g and put in an environment of 40 ° C x 65% RH 3
Stored for months. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 7.

Examples 115 to 118 The PVA meltblown nonwoven fabric obtained in Example 12 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at the temperature shown in Table 7. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 7 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, this non-woven fabric
Create a bag of 5 x 15 cm and use a commercially available pesticide (Lidomill MZ)
Wettable powder) 20g and put in an environment of 40 ° C x 65% RH 3
Stored for months. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 7.

Examples 119 to 122 The PVA meltblown nonwoven fabric obtained in Example 13 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at the temperatures shown in Table 7. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 7 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, this non-woven fabric
Create a bag of 5 x 15 cm and use a commercially available pesticide (Lidomill MZ)
Wettable powder) 20g and put in an environment of 40 ° C x 65% RH
Stored for months. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 7.

Examples 123 to 126 The PVA meltblown nonwoven fabric obtained in Example 14 was run while being in contact with a rotating metal flat roll at a surface speed of 5 m / min, and calendered at a temperature shown in Table 7. Was done. At this time, the time during which the roll and the nonwoven fabric were in contact was about 8 seconds. Table 7 shows the air permeability and breaking strength of the obtained nonwoven fabric. In addition, this non-woven fabric
Create a bag of 5 x 15 cm and use a commercially available pesticide (Lidomill MZ)
Wettable powder) 20g and put in an environment of 40 ° C x 65% RH 3
Stored for months. Three months later, the pesticide was removed from the nonwoven fabric, and the breaking strength in water was measured. The results are shown in Table 7.

Comparative Examples 15 and 16 The nonwoven fabric of Example 1 was calendered in the same manner as in Example 71 except that the surface temperature of the roll was changed.
Table 7 shows the calender temperature, the air permeability and the breaking strength of the obtained nonwoven fabric.

[0093]

[Table 7]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // D01F 6/14 D01F 6/14 Z F term (reference) 4J002 BE021 DE056 FD010 FD020 GA00 GG02 GK01 4L035 BB31 EE01 EE04 FF05 HH10 4L047 AA16 AB03 AB07 CA19 CB01 CB08 CB10 CC15 EA05

Claims (8)

[Claims] 1. A viscosity-average degree of polymerization of 200 to 500, a saponification degree of 90 to 99.99 mol%, and a molar fraction of a central hydroxyl group of three hydroxyl groups in a triad display with respect to a vinyl alcohol unit of 66 to 99.9 mol%. Melting point 16
0 ° C. to 230 ° C., alkali metal ion (B) is 0.0003 with respect to 100 parts by weight of polyvinyl alcohol (A).
A water-soluble nonwoven fabric for agrochemical packaging, characterized in that the nonwoven fabric is a melt-blown nonwoven fabric made of polyvinyl alcohol containing 〜1 part by weight and has a breaking strength of 10 g / 5 cm or less when the nonwoven fabric is immersed in water at 20 ° C. 2. The nonwoven fabric according to claim 1, wherein the polyvinyl alcohol is a modified polyvinyl alcohol containing 0.1 to 25 mol% of α-olefin units and / or vinyl ether units having 4 or less carbon atoms. 3. The nonwoven fabric according to claim 2, wherein the polyvinyl alcohol is a modified polyvinyl alcohol containing 3 to 20 mol% of ethylene units. 4. The content of 1,2-glycol bond is 1.
The nonwoven fabric according to any one of claims 1 to 3, which is 2 to 2.0 mol%. 5. The nonwoven fabric according to claim 1, which disintegrates with water at 5 ° C. to 30 ° C. 6. The fiber constituting the nonwoven fabric has an average fiber diameter of 2
The nonwoven fabric according to any one of claims 1 to 5, wherein the nonwoven fabric has a pore size of 0 µm or less and a permeability of 100 cc / cm ² / sec or less. 7. The nonwoven fabric according to claim 1, wherein an embossing treatment or a calendering treatment is performed. 8. An agricultural chemical packaging bag comprising the nonwoven fabric according to claim 1.