JP2637814B2 - Polyolefin nonwoven sheet for plant growth - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyolefin nonwoven fabric sheet for growing plants.

[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. "

[Problems to be Solved by the Invention] However, the nonwoven sheet described in Japanese Patent Publication No. 59-20325 satisfies the above-mentioned respective properties, but is required to be a nonwoven sheet having better performance. Is no different.

The present invention has been made under such a background, and an object of the present invention is to provide a nonwoven fabric sheet which is most suitable for growing plants and which can be easily formed.

[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 mixing and mixing PP-PE composite fiber composed of polypropylene and polyethylene and polyolefin staple fiber. A polyolefin nonwoven fabric sheet for growth was used.

[Action]

Polypropylene and polyethylene used in the present invention
The following can be exemplified as PP-PE composite fibers.

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 include a layer structure, and a two-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.
JP-B-55-483 can be referred to, however, in the present invention, PP-PE composite fibers other than such examples can of course be suitably used.

What can be said generally in common for these PP-PE composite fibers is that
Good thermal adhesion, low thermal shrinkage, good dimensional stability, noble and porous.
These properties greatly contribute to the performance required of the nonwoven fabric sheet for growing plants. In the present invention, the required performance of the non-woven fabric sheet for growing plants can be further improved by mixing short polyolefin fibers with such PP-PE composite fibers.

Here, the polyolefin short fiber used in the present invention will be described.

Polyolefin short fibers include polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-1
Examples thereof include polyolefin resins composed of one or more α-olefins such as -butene copolymer and ethylene-4-methyl-1-pentene copolymer, and among them, polyethylene fibers are preferable. The polyethylene constituting such a polyethylene fiber is a homopolymer of ethylene, or ethylene and another α-olefin of 20 mol% or less, preferably 15 mol% or less, for example, propylene, 1-butene,
-Hexene, 1-octene, 1-decene, 4-methyl-
It is a copolymer with one or more α-olefins such as 1-pentene, and is a polymer mainly composed of ethylene.

Examples of the polyolefin short fiber include a short fiber obtained by melt-spinning such a polyolefin resin by various methods and then cutting, a split yarn obtained by opening a polyolefin resin film, and a pulp obtained by a flash spinning method. An example is a state-of-the-art material (referred to as synthetic pulp).

Among these, the shape of the synthetic pulp is excellent in terms of uniform mixing with the PP-PE composite fiber. 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 adhesiveness to the thermoplastic short fibers deteriorates. 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 monobalmitate, sorbitan sesquioleate, etc.), polyoxyethylene sorbitan fatty acid ester And glycerin fatty acid esters (such as glycerin monostearate).

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 spurted polyolefin pulp containing from about 0.05 to 3% by weight of nonionic or anionic lubricant 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 copolymers of propylene with other 1-olefins 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 sulfate, 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.

To make the nonwoven sheet of the present invention, the PP-PE composite fiber and the polyolefin short fiber are cut to an appropriate length,
Or beating.

The cut or beaten PP-PE conjugate fiber and polyolefin staple fiber should be 10 to 80% by weight, preferably 30 to 60% by weight, based on the total weight of the polyolefin staple fiber. To obtain a raw material fiber, add a dispersant, stir and disperse in water to obtain a raw material liquid having a fiber concentration of about 1.5%.

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, it is possible to use an intermediate PVA fiber which has not been subjected to heat treatment and acetalization and is an intermediate in the production of vinylon.

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 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, a polyolefin short fiber is mixed with the PP-PE composite fiber, and since the polyolefin short fiber has been subjected to the hydrophilic treatment, it is easily dispersed in water, so that the papermaking is easy. Can be. 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, since the heat setting is performed by mixing the PP-PE composite fiber, there is an advantage that the heat setting can be performed in a temperature range which is considerably wider than that of the polyethylene fiber alone. That is, when the raw material fiber is a single polyolefin fiber, when heat setting is performed at a temperature equal to or higher than the melting point of the polyolefin fiber, the fiber is melted and the nonwoven fabric becomes a film, but in the present invention, the PP-PE composite fiber is used. Because it is used, PP component does not melt even if PE component melts,
The whole nonwoven fabric does not become a film. Further, the nonwoven fabric sheet of the present invention may be mixed with a vegetable fiber material in an amount of 10% by weight or less in order to improve the heat setting property and the like.

The temperature of the heat set is 130-160 ° C, preferably 140-1
50 ° C is good.

In the present invention, the nonwoven sheet having many fine pores is obtained by mixing a noble and porous PP-PE composite fiber and a polyolefin staple fiber to make the polyolefin staple fiber 10 to 80% by weight based on the total weight. It is excellent in water permeability, air permeability, and water retention, and has a high surface smoothness and an excellent root blocking ability.

In addition, the coefficient of friction of the surface of the obtained nonwoven
It is shown in the table. Mixing vegetable natural fibers increased the coefficient of friction, which made cutting easier.

〔Example〕

 Hereinafter, embodiments of the present invention will be described.

As the PP-PE composite fiber, a 3d fineness composite fiber (trade name ES fiber, manufactured by Chisso Corporation) having a core-sheath structure in which polypropylene is the core and polyethylene is the sheath is a fiber length of 10 to 20.
mm, a polyethylene pulp having an average fiber length of 0.9 mm and an average fiber diameter of 10 μmφ (trade name SWP
(Registered trademark) UL410, manufactured by Mitsui Petrochemical Industry Co., Ltd.] as vegetable natural fiber, fiber length 3-6 mm, fineness 4-5
Experiment No. 1 (weight ratio / = 50 /
50), Experiment No. 2 (weight ratio /// = 50/40/10)
Seed paper was made and its properties and the friction coefficient were measured. Here, the tensile test was performed under the conditions of a room temperature of 20 ° C. and a humidity of 60% RH when dry, and after immersion in water at 20 ° C. for 30 minutes when wet.
The pore size was measured in anhydrous methyl alcohol (first grade reagent) by the valve point method. The results are shown in Table 1 and 2
It is shown in the table.

When the heat setting temperature was changed, heat setting of the nonwoven fabric blended with the above was possible in the range of 140 to 150 ° 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〕

INDUSTRIAL APPLICABILITY The nonwoven fabric sheet for growing plants of the present invention has excellent water permeability, air permeability, and water retention, does not pass through the roots of seedlings, and has good rooting of seedlings. Also, it is easy to make paper and heat set easily.

Claims (1)

(57) [Claims] (1) It is composed of polypropylene and polyethylene.
PP-PE composite fiber, and a nonwoven sheet obtained by blending polyolefin short fibers, the polyolefin short fibers,
A polyolefin nonwoven fabric sheet for cultivating plants, wherein the content is 10 to 80% by weight based on the total weight.