JP3583539B2 - Method for manufacturing porous hose - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a porous hose. Specifically, a method of manufacturing a porous hose having a number of small holes in a peripheral wall, which is used for underground irrigation, watering, fertilization, chemical application, air supply, and drainage of agriculture, horticulture, and greening facilities. About.
[0002]
[Prior art]
There are a soft hose and a hard hose depending on the material of the porous hose having a small hole used for underground type irrigation or watering. In the case of a soft hose, there are drawbacks such as poor shape retention, easy torsion and kinking, and consequently, residual liquid adheres to the inside of the hose due to an adhesive action and causes clogging. On the other hand, a hard hose does not have the same drawbacks as a soft hose because of its strong shape retention, but has a drawback of poor storage, transportability and workability.
[0003]
In order to improve these drawbacks, a powder mixture obtained by mixing rubber powder, olefin-based resin powder and foaming agent powder, which has been finely divided by mechanical treatment, is foam-formed by an extrusion molding method so that air bubbles between the rubber powders are communicated. Thus, a method of exuding water from the communication portion is known (for example, Japanese Patent Publication No. 7-53406).
[0004]
[Problems to be solved by the invention]
However, the method disclosed in Japanese Patent Publication No. 7-53406 has a problem that it is extremely troublesome because it is necessary to pulverize rubber or resin into 20 to 80 meshes and mix them evenly.
In addition, since a powder agent mixed with a foaming agent in advance is used, the degree of communication (foaming degree) can only be adjusted in the middle of molding by changing the take-up speed. Since it is a product, care must be taken in handling, and in addition, there is a manufacturing problem that it is expensive.
[0005]
Therefore, an object of the present invention is to provide a method of manufacturing a porous hose which does not require particularly complicated operations, can easily adjust the degree of foaming, and is excellent in handling safety.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing a porous hose of the present invention is a method for producing a porous hose by foaming and extruding a thermoplastic elastomer, and an extruder filled with a thermoplastic elastomer. The thermoplastic elastomer is extruded while pouring water used as a foaming agent under a predetermined pressure into a cylinder of the cylinder to form an open cell structure through which a liquid and / or a gas can permeate on the peripheral wall. ).
[0007]
In addition, it is preferable that the temperature of the thermoplastic elastomer is set to 150 ° C. or more and foam extrusion is performed (claim 2).
[0008]
Further, the amount of water to be injected is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the thermoplastic elastomer.
[0009]
The Shore hardness of the thermoplastic elastomer is preferably 50A to 80D (Claim 4).
[0010]
According to the present invention, since there is no need to powder or mix the raw materials, the operation is simple, and since water is used as a blowing agent instead of using a chemical blowing agent, safety is also excellent. Also, since the water is foamed and extruded while pouring the water into the cylinder of the extruder, the degree of foaming can be easily adjusted by changing the amount of water injected.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
A method for manufacturing the porous hose of the present embodiment will be described.
(1) First, a thermoplastic elastomer is charged into a cylinder of an extruder. The extruder is an extruder with a screw, and is connected to a high-pressure liquid injection device. The high-pressure liquid injection device includes a commercially available pump, an on-off valve, a pressure gauge, and the like.
[0012]
Examples of the thermoplastic elastomer used herein include styrene-based, polyolefin-based, polyvinyl chloride-based, polyurethane-based, polyester-based, polyamide-based, 1,2-polybutadiene-based, trans polyisoprene-based, fluororubber-based, chlorinated polyethylene-based, It includes all thermoplastic elastomers such as dynamically crosslinked systems.
The thermoplastic elastomer preferably has a Shore hardness of 50A to 80D (ASTM D2240). If the Shore hardness is less than 50A, the extruded molded porous hose has a weak self-shape retention force, whereas if it is larger than 80D, the hose becomes too hard, resulting in poor storage, transportability and workability. It is.
[0013]
(2) Then, water used as a foaming agent is injected under predetermined pressure into a cylinder of the extruder through a high-pressure liquid injection device, and the thermoplastic elastomer and water are mixed by rotating a screw in the extruder. And foam extrusion of a thermoplastic elastomer.
At this time, it is preferable that the temperature of the thermoplastic elastomer is set to 150 ° C. to 220 ° C. to perform foam extrusion molding. When the temperature is lower than 150 ° C., the viscosity of the thermoplastic elastomer increases, and the degree of expansion of the foaming agent (water) decreases. For this reason, the degree of foaming becomes low, and a sufficient open cell structure cannot be obtained on the peripheral wall of the hose, and liquid and / or gas hardly permeate. On the other hand, if the temperature is higher than 220 ° C., the extruded thermoplastic elastomer is easily stretched, and as a result, bubbles are easily crushed and liquid and / or gas are hardly permeated.
[0014]
Further, the injection amount of water is preferably 0.05 to 5 parts by weight based on 100 parts by weight of the thermoplastic elastomer. If the injection amount of water is less than 0.05 parts by weight, the bubbles are not sufficient, and the liquid and / or gas is difficult to permeate from the inside to the outside of the hose. This is because molding becomes difficult. It is most preferable that the amount of water injected be 0.1 to 2 parts by weight based on 100 parts by weight of the thermoplastic elastomer. The liquid to be injected may be other than water, such as urea water.
[0015]
As shown in FIG. 1, the partial cross section of the water foamed and extruded hose has a continuous cell structure through which a liquid and / or a gas can pass, that is, a communication part 4 in which the cell parts 3 are connected to each other. It is formed on the peripheral wall of the hose molded with the elastomer 5. This is compared with FIG. 2 showing a partial cross section of a hose extruded from the mixed powder agent shown in the conventional example, and the water foamed extruded hose according to the present embodiment has a continuous portion occupying the communicating portion 4, that is, the continuous wall occupying the peripheral wall. It can be seen that the degree of bubbles is large and the amount of seeping water is large. In FIG. 2, reference numeral 1 denotes a rubber powder, 2 denotes an olefin resin powder, 3 denotes a bubble portion, and 4 denotes a communication portion.
[0016]
In addition, a test comprising the hose foamed and extruded according to the present embodiment (in the case of a water injection amount of 0.5% by weight and in the case of a water injection amount of 1.0% by weight) and the hose formed by extrusion molding of the mixed powder shown in the conventional example. the body 8 and facilities horizontally to each 50m ground, as shown in FIG. 3, connected to the bleeding amount of the measuring device, inlet pressure gauge 7 is water so that 1.0 kgf / cm ² faucet When water was flowed from No. 6, the relationship between the measured distance (m) and the amount of oozing (ml / min / m) was as shown in FIG. Reference numeral 9 denotes a terminal pressure gauge. From this, it can be seen that the water-blowing extruded hose according to the present embodiment has a larger water seeping amount.
[0017]
【The invention's effect】
As described above, according to the present invention, there is no need to powder or mix the raw materials, so that the operation is simple, and since water is used as a blowing agent instead of using a chemical blowing agent, safety is also excellent. , And it is cheap. In addition, since the water is foamed and extruded while pouring the water into the cylinder of the extruder, the degree of foaming can be easily adjusted by changing the amount of injected water, and the adjustment range is large. Since the molded hose is a single thermoplastic elastomer, it can be easily recycled, and can be manufactured at low cost because the process is shortened.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view of a hose obtained by water-blowing extrusion molding of a thermoplastic elastomer 5 according to an embodiment of the present invention.
FIG. 2 is a partial cross-sectional view of a hose in which a mixed powder is extruded according to a conventional example.
FIG. 3 is an external view showing an apparatus for measuring a seepage amount.
FIG. 4 shows a hose (water injection amount of 0.5% by weight and water injection amount of 1.0% by weight) of a thermoplastic elastomer 5 according to an embodiment of the present invention, and a conventional example. 7 is a graph showing the relationship between the measurement distance (m) and the amount of oozing (ml / min / m) for a hose extruded from a mixed powder agent.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rubber powder 2 Olefin resin powder 3 Bubble part 4 Communication part 5 Thermoplastic elastomer 6 Water tap 7 Inlet pressure gauge 8 Specimen 9 Terminal pressure gauge

Claims (4)

A method for producing a porous hose by foaming and extruding a thermoplastic elastomer, wherein a water used as a foaming agent is injected under a predetermined pressure into a cylinder of an extruder filled with the thermoplastic elastomer while heating. A method for producing a porous hose, comprising extruding a plastic elastomer to form an open-cell structure on a peripheral wall through which a liquid and / or a gas can pass. The method for producing a porous hose according to claim 1, wherein the thermoplastic elastomer is foamed and extruded at a temperature of 150 ° C or higher. The method for producing a porous hose according to claim 1 or 2, wherein the amount of the water injected is 0.05 to 5 parts by weight based on 100 parts by weight of the thermoplastic elastomer. The method according to any one of claims 1 to 3, wherein the thermoplastic elastomer has a Shore hardness of 50A to 80D.

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