JPH07274764A - Buoyancy material - Google Patents

Abstract

PURPOSE:To obtain a buoyancy material having high buoyancy, excellent elasticity, not being destroyed even by impact, stably usable for a long period of time, further readily producible. CONSTITUTION:Superimposed faces of foam sheets (30 times expansion ratio, 8mm thickness and 1050mm width) of a cross-linked low-density polyethylene are thermally fused into a roll-like rolled material 2. A low-foam sheet 3 (10 times expansion ratio, 4mm thickness and 1050mm width) is thermally fused to the outside of the rolled material 2 similarly and rolled triply to give the objective buoyancy material. The outer diameter of the buoyancy material is 500mm. A winding core is not used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buoyancy material used as a buoy, a cushioning material, a drainage pipe floater, a pontoon or the like for fisheries and work vessels.

[0002]

2. Description of the Related Art Styrofoam moldings and polyurethane foams have hitherto been used as buoyancy materials for aquaculture cages and buoys for fishing in the ocean and rivers. A large buoyancy can be obtained by using styrofoam, however, there is a problem that the weather resistance and impact resistance are so poor that the buoyancy is reduced due to the holes such as crabs.

Therefore, it is considered to cover the outside of the polystyrene foam with a hard material. For example, Jikkou Sho 59-3002
Japanese Patent Publication No. 3 discloses a float in which the outside of styrene is covered with non-foamed polyethylene. In addition to the above, there is also used a styrofoam molded body coated with a resin mortar mixed with a fiber reinforced synthetic resin or an inorganic filler.

[0004]

In order to manufacture the float as described in the above publication, first, a molded body obtained by foaming polystyrene with steam in a molding die is manufactured, while a polyethylene resin container as a covering material is prepared. It requires large-scale facilities and processes of manufacturing and loading the foamed molded product into this container. The same applies to the case of polyurethane foam.

If the container is made of a hard material such as a polyethylene resin molded product, resin mortar, or fiber reinforced synthetic resin, it is easily broken by a ship collision or the like and becomes heavy. When the container is broken and the Styrofoam is exposed, the Styrofoam is not elastic and is more easily broken. In addition, there is a problem that the deterioration progresses quickly and it cannot be used for a long time.

The present invention solves the above-mentioned problems of the prior art, has a large buoyancy and a high elasticity, does not break even when shocked, can be used stably for a long period of time, and is easy to manufacture. The purpose is to provide a buoyancy material.

[0007]

The buoyancy material of the present invention is a wound body obtained by winding a foamed sheet of closed cells made of polyethylene in a roll shape, and the superposed surface of the foamed sheet by winding is thermally bonded. It is characterized by being done.

The polyethylene used in the present invention is mainly low-density polyethylene, and a propylene resin, an ethylene-vinyl acetate resin, etc. may be appropriately mixed if necessary for adjusting hardness and heat resistance. This polyethylene is preferable because when it is made into a foam, the polyethylene is fine and uniform, and has excellent heat resistance and cushioning properties.

The foamed sheet is a foamed body composed of closed cells, and the expansion ratio is preferably 5 to 40 times. If it is less than 5 times, the buoyancy will be insufficient, and if it exceeds 40 times, the strength will be low and it will be easily broken. The thickness of the foam sheet is preferably about 2 to 10 mm. If the thickness is less than 2 mm, the ratio of the thickness of the bubbles crushed on the surface at the time of thermal bonding becomes large with respect to the thickness of the foamed sheet to affect the buoyancy, and the manufacturing efficiency decreases. If it exceeds 10 mm, the work of winding it in a roll shape becomes difficult, and the manufacturing efficiency decreases.

The foamed sheet is wound into a roll to form a wound body. Usually, such a wound body is wound around a core such as a paper tube, but the core of the present invention is not particularly required. However, the core may be manufactured, transported, or fixed as necessary. You can use it.

The diameter and length of the wound body are not particularly limited because the buoyancy required depends on the purpose of use, but usually the diameter and length are about 300-1500 mm and the length is 300-200.
The thing of about 0 mm is used.

Although the setting of the buoyancy varies depending on the purpose of use and the object, the expansion ratio, thickness, and
It can be freely selected by adjusting the length, that is, the diameter of the wound body and the width of the wound body. The length of the rolled body may be adjusted by a method in which the width of the foamed sheet is adjusted to a predetermined length and then wound, or the wound body may be cut into a predetermined length.

Joining of the overlapping surfaces of the foamed sheets formed into a roll-shaped roll is performed by heat fusion or adhesion with a hot melt adhesive. The joining by heat fusion can be easily performed by winding the surface of the foamed sheet, which is the inner side when wound, in a state where only the surface is melted by gas burner, electric heat, infrared rays or the like. As the hot melt adhesive, a commonly used general adhesive can be used. Since the purpose of the thermal bonding is to prevent the shape of the foamed sheet from being collapsed after the foamed sheet is formed into a rolled body, the overlapping surface of the foamed sheet may be entirely or partially bonded.

The buoyancy material obtained as described above can be used as it is without any problem. However, it is preferable to wrap a protective sheet as a reinforcement to withstand friction and impact with ships and ropes during use, and to supplement the weather resistance of the foamed sheet. For example, the same quality as the above foam sheet, 5 to 15
It is conceivable to wind a low-foaming sheet called double-foaming while thermally bonding it once to several times.

Although a non-foamed sheet may be used as the protective sheet, a low-foamed sheet is preferable from the viewpoint of increasing buoyancy and providing cushioning properties. When a foamed sheet or a non-foamed sheet of polyethylene resin is used as the protective sheet, only the outermost layer or the protective sheet in the vicinity of the outermost layer is aged by sunlight or the like, and it is possible to prevent the inner layer foamed sheet from being aged.

In order to facilitate the handling work or secure the fixing of the buoyancy member to the installation location, it is preferable to pass a mandrel having holders at both ends through a portion corresponding to the winding core. The mandrel is not particularly limited as long as it is a lightweight material such as a metal tube and a hard synthetic resin tube, has excellent weather resistance, and has sufficient strength against bending force and impact.

[0017]

Since the buoyancy material of the present invention comprises a closed-cell foam sheet, it does not absorb water and has excellent buoyancy and durability.
Further, since the foamed sheet is made of polyethylene, it has excellent flexibility and cushioning property and is not destroyed even when a ship or the like collides. Moreover, since the overlapping surfaces of the foamed sheets are heat-bonded, the shape is stable and does not collapse.

Furthermore, since the foam sheet is wound in a roll shape, the buoyancy can be freely set by adjusting the length of the foam sheet to be wound. Also in manufacturing, since the foamed sheet is only thermally bonded while being wound, it can be efficiently manufactured with a very simple facility.

[0019]

Embodiments of the buoyancy material of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of the buoyancy material 1 of the present invention, in which a laminated sheet of a cross-linked low-density polyethylene foam sheet (foaming ratio: 30 times, thickness: 8 mm, width: 1050 mm) is heat-bonded into a roll shape. The low-foamed sheet 3 of low-density polyethylene cross-linked to the outside of the roll 2 (expansion ratio 10 times, thickness 4 mm, width 1).
050 mm) is similarly heat-bonded and wound three times. The outer diameter of this buoyancy member 1 is 500 mm. No core is used.

FIG. 2 is a cross-sectional view of the buoyancy member 1 of FIG. 1 with the mandrel 6 attached, and is made of a metal having discs 61, 61 at both ends and annular holders 62, 62 on the outside thereof. The mandrel 6 is inserted into the shaft core of the buoyancy member 1. One end of the mandrel 6 is formed as a male screw portion 63 and is joined to a female screw of the short pipe 64 by screwing. A rope or the like is passed through the holders 62, 62 for use.

FIG. 3 is an explanatory view showing a state in which the buoyancy material 1 is manufactured. One side of the foamed sheet 21 is a roll 5.
It is wound around the paper tube 22 while being fused by being heated and melted by the gas burner 4 above. Then, the low foam sheet (not shown) was wound from the outside of the roll 2 in the same manner for three rounds while thermal bonding. The wound state was left for 24 hours for cooling, and the buoyancy material was obtained by cutting with a vertical cutter to a length of 800 mm in the width direction of the roll.

When the above buoyancy material 1 was used as a buoy for aquaculture cages, it had a large buoyancy and a high flexibility and cushioning property, so it would not crack or lose its shape even after a collision with a ship even after 5 years. It could be used without any abnormalities.

[0023]

The buoyancy material of the present invention has the above-mentioned constitution and, since it is made of a foamed sheet of closed cells, has no water absorption and can obtain a large buoyancy. Further, it is excellent in flexibility and cushioning property, and is not broken even if a ship collides with it, and has excellent long-term durability. Moreover, since the overlapping surfaces of the foamed sheets are heat-bonded, the shape is stable and does not collapse.

Furthermore, the buoyancy can be freely set by adjusting the length of the foamed sheet to be wound. Even in manufacturing, it is possible to efficiently manufacture with a very simple facility because it is only thermal bonding while winding the foamed sheet, buoyancy material such as aquaculture cage, fishing buoy, work boat floater, pontoon etc. It can be used as various buoyancy materials.

[0025]

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a buoyancy material of the present invention.

FIG. 2 is a sectional view showing a state where a core rod is attached to the buoyancy member of FIG.

FIG. 3 is an explanatory view showing a method for manufacturing a buoyancy material of the present invention.

[Explanation of symbols]

 1: Buoyancy material 2: Rolled body 3: Low foam sheet 4: Gas burner 5: Roll 6: Metal rod 21: Foam sheet 22: Paper tube 61: Disc 62: Holder 63: Male screw part 64: Short tube

Claims (1)

[Claims] 1. A buoyancy material, which is a wound body formed by winding a foamed sheet of closed cells made of polyethylene in a roll shape, and overlapping surfaces of the foamed sheet by winding are thermally bonded. .