JP2574846B2 - Non-woven fabric underlay sheet for raising seedlings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a nonwoven fabric underlay sheet for raising seedlings.

[Conventional technology]

Conventionally, a cultivation method of a plant in which seedlings are formed by laying embankments on the underlay of a nonwoven sheet, growing rice and flowering seedlings in the seedbed, removing the nonwoven sheet after some growth and transplanting the seedlings together with soil. However, the following performance is required for the nonwoven fabric sheet used in such a cultivation method.

It has good water permeability and air permeability, does not pass the roots to the soil below to protect the seedlings from soil diseases, can grow well-rooted seedlings, can easily perform root cutting work at the time of transplantation, etc. is there.

By the way, as such a nonwoven sheet,
What is described in 59-20325 is known. This non-woven fabric sheet is a thin film made of a non-corrosive non-woven sheet material, and the thin film is formed with a myriad of bendable micropores penetrating substantially continuously from the front surface to the back surface. And the micropores have an average diameter of 30 microns or less in at least a part of the cross section of the path. "

Further, as another example of such a nonwoven fabric sheet, Japanese Patent Publication No. 59-6613 discloses wood pulp, paper cake, plant fiber,
The main raw material is a fibrous material (natural fiber) such as bark, and a thermosetting resin such as urea resin, urea melamine resin, and phenol resin, or a thermoplastic resin such as polyethylene or polypropylene. There is described a seedling raising mat having a specific gravity of 0.05 to 0.3, which is blended at 30% and heat molded. It is said that the amount of the synthetic resin is preferably as low as possible within a range of 5 to 30% in order to impart air permeability and water absorption to the seedlings (see the above-mentioned publication, page 2, left column, no.
44 lines-right column, 4th line on the same page).

[Problems to be solved by the invention]

The former non-woven fabric sheet described in Japanese Patent Publication No. 59-20325 satisfies the above-mentioned respective performances, but it is still required to be a non-woven fabric sheet having better performance. Since the non-corrosive material is made of only a non-corrosive material, that is, usually a synthetic resin, the emphasis is placed on preventing the invasion of pathogenic bacteria among various performances, it may be difficult to form a nonwoven fabric.

On the other hand, the latter disclosed in Japanese Patent Publication No. 59-6613 tends to be mainly composed of natural fibers, and reveals the problem of being mainly composed of natural fibers, such as a decrease in the strength of the sheet itself. I do.

The present invention has been made under such a background, and makes use of the advantages of synthetic resins and natural fibers to further improve various performances required as a non-woven underlay sheet for raising seedlings in any combination of both. In addition, it has been made to make it easy to make paper.

[Means for solving the problem]

The present invention takes the following means in order to solve the above problems.

That is, the present invention is a nonwoven fabric sheet obtained by blending a polyolefin fiber including a composite fiber of polypropylene and polyethylene and a vegetable natural fiber, wherein the vegetable natural fiber is 10 to 50% by weight based on the total weight. The task has been achieved.

[Action]

Here, the polyolefin fiber used in the present invention, regardless of crystalline, amorphous, low density polyethylene, high density polyethylene, polypropylene, poly 1-butene,
Α such as poly 4-methyl-1-pentene or ethylene, propylene, 1-butene, 4-methyl-1-pentene, etc.
-Polyolefin fibers such as random or block copolymers of olefins, and these are used alone or in combination.

As the polyolefin fiber suitably used in the present invention, a composite fiber of polypropylene and polyethylene (hereinafter, referred to as composite fiber
PP-PE composite fiber) and a blend of the PP-PE composite fiber with another fiber mainly composed of polyolefin fiber (hereinafter referred to as PO fiber).

The PP-PE composite fiber is a composite of a component composed of substantially crystalline polypropylene (hereinafter, referred to as a PP component) and a component composed of polyethylene (hereinafter, referred to as a PE component). 2 having a core-sheath structure, a PP component and a PE component,
Examples thereof include a layer structure, and a three-layer structure in which a PP component is sandwiched between PE components. Further, in each structure, each layer does not need to be continuous.

Crystalline polypropylene constituting the PP-PE composite fiber,
Homopolymer of propylene or 10 mol% with propylene
Or less, preferably 5 mol% or less of other α-olefin,
For example, it is a copolymer with one or two or more α-olefins such as ethylene, 1-butene, 1-hexene, 1-octene, and 1-decene. Such crystalline polypropylene is
Normally, MFR (L) (ASTM D1238, L) is 0.1-50g / 10mi
n, preferably 0.5 to 30 g / 10 min, melting point (ASTM D3418)
Is 135 ° C. or higher, preferably 145 ° C. or higher.

On the other hand, polyethylene constituting the PP-PE composite component is a homopolymer of ethylene or ethylene and 20 mol% or less, preferably 15 mol% or less of other α-olefin,
For example, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 4-methyl-1-pentene, etc.
Or two or more α-olefins. Such polyethylenes are usually MFR (E) (ASTM D
1238, E) is 0.1 to 100 g / 10 min, preferably 0.5 to 60 g / 10
min, melting point is 90 ° C or higher, preferably 100 ° C or higher.

Examples of the specific constitution and production method of the PP-PE composite fiber include, for example, JP-B-52-37097 and JP-B-55-17807.
Japanese Patent Publication No. 55-483 can be referred to, but the present invention is not limited to such an example.

Further, it is preferable that the melting point of polyethylene as the other component is lower than the melting point of polypropylene by 20 ° C. or more. Then, by treating the composite fiber having such a configuration at a temperature higher than the melting point of polyethylene and lower than the softening point of polypropylene, a nonwoven fabric in which the bonding points of the fibers are fused can be obtained.

What can be said generally in common for these PP-PE composite fibers is that
Good heat adhesion and low heat shrinkage, therefore good dimensional stability, bulky and porous.
These properties greatly contribute to the performance required of the nonwoven fabric underlaying sheet for raising seedlings.

In the present invention, the required performance of the nonwoven fabric underlay sheet for raising seedlings is further improved by mixing a fiber mainly composed of polyolefin (hereinafter referred to as PO fiber) together with such PP-PE composite fiber as the polyolefin fiber. be able to.

As the PO fiber, in addition to the single fibers of the various polyolefins exemplified above, a composite fiber or a synthetic pulp mainly composed of polyolefin, and a polyethylene fiber is preferable because of its compatibility with the PP-PE composite fiber. The polyolefin fiber may be crimped or non-crimped, if necessary.
Denier can be changed, and the final bulkiness and the like of the obtained nonwoven fabric can be changed by these changes.

As the PO fiber, from one or two or more α-olefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, and ethylene-4-methyl-1-pentene copolymer Short fibers of polyolefin resin can be used.
Such a polyolefin resin is melt-spun by various methods and then cut into short fibers, split yarn obtained by opening a resin film, or pulp-like material obtained by flash spinning (referred to as synthetic pulp). ) Is exemplified.

Among them, the shape of synthetic pulp is excellent in terms of uniform mixing with vegetable natural fiber materials. The method for producing synthetic pulp is described, for example, in Japanese Patent Publication No. 52-47049.In the present invention, in particular, synthetic pulp is preferably used as synthetic pulp at the time of production, and synthetic pulp having polyvinyl alcohol adhered to the surface thereof is preferably used. .

In the production of synthetic pulp, the use of polyvinyl alcohol not only improves the spinnability in the flash spinning method, but also imparts hydrophilicity to the obtained fibers.

In order to further improve the hydrophilicity, it is important to treat the polyolefin short fibers with a nonionic surfactant. In the case of the flash spinning method, the treatment with the surfactant is preferably performed by adding the surfactant to the water slurry since the pulp-like short fibers become a water slurry at the stage of production. That is, the treatment with the surfactant is performed by dewatering the polyolefin short fibers after forming a slurry mixture of water containing the nonionic surfactant.

The nonionic surfactant used at this time is (a) HLB
Is in the range of 2 to 20, and (b) the melting point (JIS K 0
064) must be equal to or higher than the temperature at which the slurry mixture is dehydrated.

If the HLB is out of this range, sufficient hydrophilicity cannot be imparted. On the other hand, if the melting point is lower than the temperature at the time of dehydration of the slurry mixture, it is in a liquid state in the water slurry, so that the adhesion to short polyolefin fibers is deteriorated. Since the temperature at the time of dehydration of the water slurry is usually about 10 to 50 ° C., a surfactant having a melting point in the range of about 20 to 80 ° C. is used.

As the nonionic surfactant satisfying the above conditions, for example, polyoxyethylene alkyl ether,
Polyoxyethylene alkyl phenyl ether (polyoxyethylene nonyl phenyl ether, etc.), polyoxyethylene fatty acid ester, sorbitan fatty acid ester (sorbitan monooleate, sorbitan monopalmitate, sorbitan sesquioleate, etc.), polyoxyethylene sorbitan fatty acid ester, Glucerin fatty acid esters (such as glycerin monostearate) can be exemplified.

Among these, glycerin fatty acid esters having an HLB of 2 to 6 and a melting point of 40 to 90 ° C., sorbitan fatty acid esters of an HLB of 2 to 8 and a melting point of 20 to 80 ° C., HLB of 8 to 20, and a melting point of 10 to 5
Polyoxyethylene alkyl phenyl ether at 0 ° C. is particularly desirable.

Also, apart from the above, as another example of synthetic pulp,
Illustrative are spunted polyolefin pulp containing from about 0.05 to 3% by weight of a nonionic or anionic wetting agent having a molecular weight of less than 8000 (based on the weight of the polyolefin described below).

Spouted polyolefin pulp is a very fine, highly branched, discontinuous fibril made from polyolefin that has a large area (3-5 cm ² / g) and low density (about 0.2 g / c).
c), having an average length of about 1 mm and an average diameter of about 5 to 40μ.

Examples of the raw material polyolefin of the spouted polyolefin pulp include polyethylene, polypropylene, ethylene propylene copolymer, and a copolymer of propylene with another α-olefin such as 1-butene, 4-methyl-1-pentene, 1-hexene, and the like. Those in which maleic anhydride or a styrene compound is grafted to any of these polymers can also be used. Of these, polyethylene is preferred.

The wetting agent used is one or more anionic or nonionic ones, such as polyoxyethylene monostearate, bis (hydroxyethyl) tallowamine, sodium dioctylsulfosuccinate,
Examples thereof include polyoxyethylene dioleate ester, sodium lauryl sulfonate, ethoxylated sorbitan laurate, and sodium alkyl sulfonate.
Of these, ethoxylated sorbitan laurate and sodium alkyl sulfonate are preferred. The treatment with the wetting agent is performed by a known dipping method, a spraying method, or by adding a wetting agent to the pulp slurry as described above.

As the polyolefin fiber constituting the nonwoven fabric sheet of the present invention, the PP-PE composite fiber and the PO fiber, especially the synthetic pulp mainly composed of the PP-PE composite fiber and polyethylene, 9: 1
A mixture of 1: 9 (weight ratio), preferably 7: 3〜4: 6 (weight ratio) is preferable because it can widen the temperature range of heat setting and is excellent in papermaking properties.

Next, the plant natural fibers used in the present invention are flax,
Timer, jute, bast fiber such as ramie, sisal fiber, hard fiber (leaf vein fiber) such as manila fiber, cotton and the like, and pulp and other cellulosic fibers can be exemplified. Further, as pulp, wood pulp, bamboo pulp,
Kraft pulp and the like can be exemplified, and these vegetable natural fibers are used alone or in combination.

In addition, cellulose fibers such as acetate and rayon may be mixed, but these are close to vegetable natural fibers because they are mainly composed of cellulose.

In making the nonwoven fabric of the present invention, these polyolefin fibers and vegetable natural fibers are cut into appropriate lengths,
Or beating. Generally, the ratio of fiber length to thickness is 500: 1
Since the paper cannot be formed by the above, the fiber length is determined to be 500: 1 or less in relation to the fineness.

Cut or beaten polyolefin fiber, vegetable natural fiber is mixed with raw natural fiber so that the vegetable natural fiber is 10 to 50% by weight, preferably 15 to 30% by weight based on the total weight, Beat this raw fiber with a beater, add a dispersant, stir, disperse in water, and add about 1.5%
To obtain a raw material liquid having a fiber concentration of about 10%.

Examples of the dispersant to be used include trolley oil mucus, sodium polyacrylate, polyethylene oxide, and polyphosphoric acid.

Next, water is further added to the raw material liquid to reduce the fiber concentration to about 0.6%.
After adding a binder as needed, impurities and insufficiently dispersed fibers are removed by a screen, and the paper is formed by a paper machine.

Here, as the binder, a heat-soluble and acetalized non-soluble PVA fiber, which is an intermediate in the production of vinylon, can be used.

As the paper machine, a well-known circular net type, long net type, or short net type can be used. The formed nonwoven sheet is dried by a dryer, heat-set by a calendar, and wound up as a product.

The basis weight of the obtained nonwoven fabric sheet is 30 to 150 g / m ² , preferably 50 to 100 g / m ² . The apparent specific gravity is 0.2-0.
9, preferably 0.4 to 0.7.

In the production process as described above, in the present invention, the plant natural fiber is mixed with the polyolefin fiber, and the plant natural fiber is hydrophilic and easily dispersed in water, so that the papermaking can be easily performed. In addition, the sheet strength when wet is increased, the transportability by the belt and the releasability from the belt are improved, and it can be said from this point that the production is facilitated.

Further, in the present invention, there is an advantage that the heat setting can be performed in a considerably wide temperature range including the melting point without regard to the melting point of the synthetic fiber. That is, when the raw material fibers are only synthetic fibers, when heat setting is performed at a temperature equal to or higher than the melting point of the synthetic fibers, the fibers melt and the nonwoven fabric becomes a film. In this case, even if the synthetic fibers are melted, the vegetable natural fibers are not melted, so that the molten resin is retained by the vegetable natural fibers, and the whole nonwoven fabric does not become a film.

Heat set temperature is 120 ~ 200 ℃, preferably 140 ~ 1
60 ° C is good.

And, in the present invention, a polyolefin fiber and a vegetable natural fiber are mixed, and the vegetable natural fiber is added to the total weight of 10 to 10%.
By setting the content to 50% by weight, a nonwoven fabric sheet having many micropores can be obtained, which is excellent in water permeability, air permeability and water retention, and excellent in root blocking ability.

Further, the coefficient of friction of the surface of the obtained nonwoven fabric sheet is 2nd.
It is large as shown in the table, which makes cutting easier. This seems to be the effect of mixing vegetable natural fibers.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

As the PP-PE composite fiber, a fineness of 1.5 d and 3 d having a core-sheath structure with polypropylene as the core and polyethylene as the sheath
A composite fiber (trade name: ES fiber, manufactured by Chisso Corporation) cut to a fiber length of 10 to 20 mm is used. As PO fiber, an average fiber length of 0.9 mm and an average fiber diameter of 10 μm are used.
mφ polyethylene pulp [Product name SWP (registered trademark) UL4
10, Mitsui Petrochemical Industry Co., Ltd.], as vegetable natural fiber, fiber length 3-6 mm, fiber length 4-5
Experiment No. 1 (/ == 60/20 /
20, using 1.5d fiber), Experiment No.2 (
// == 50/30/20, using 3d fiber) and Experiment No.3 (same composition as Experiment No.2 but with different basis weight) to measure various properties However, for Experiment No. 1, the friction coefficient was also measured. Here, the tensile test was performed under conditions of a room temperature of 20 ° C. and a humidity of 60% RH when dry.
Measured after immersion in water at 30 ° C for 30 minutes. The pore size is determined by the valve point method using anhydrous methyl alcohol (first grade reagent).
Measured in The results are shown in Tables 1 and 2.

When the heat setting temperature was changed, the heat setting of the nonwoven fabric blended with the above was 130 to 180 ° C.
Rayon fibers (vinylon binder: vinylon content 10-15%, melting point
65 ~ 80 ℃) Non-woven fabric heat setting temperature range is 90 ~
Heat setting was possible over a much wider range of temperatures than at 100 ° C.

Further, when the product name and the like were printed on the paper-made nonwoven fabric, the riding of the ink was also good.

Moreover, when actually used for plant cultivation, seedlings with good rooting could be grown, and the root cutting work at the time of transplantation could be easily performed without passing through the roots.

〔The invention's effect〕

The seedling-raising nonwoven fabric underlay sheet of the present invention is excellent in water permeability, air permeability and water retention, does not pass through the roots of seedlings, and has good rooting of seedlings. In addition, papermaking is easy, heat setting is easy, slippage is prevented by mixing natural fibers, and cutting can be easily performed.

Claims (1)

(57) [Claims] 1. A nonwoven fabric sheet obtained by mixing a polyolefin fiber containing a composite fiber of polypropylene and polyethylene with a vegetable natural fiber, wherein the vegetable natural fiber is contained in an amount of 10 to 50% by weight based on the total weight. A nonwoven fabric underlay sheet for raising seedlings.