JP3286693B2 - Pipe foam - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe-shaped foam having a ring-shaped cross section formed by fusing a plurality of strips of a thermoplastic resin foam at adjacent portions.

[0002]

2. Description of the Related Art For example, as a so-called pipe cover which is attached to a pipe for water supply or hot water supply, a pipe for cooling / heating, or other pipes for the purpose of heat insulation and buffer protection, a flexible synthetic resin molded into a cylindrical shape is used. Resin foams (ie, pipe-like foams) are commonly used. Further, this pipe-shaped foam is also used as a cushioning material or a protection material for other articles such as wood.

Conventionally, this type of pipe-shaped foam is often formed by extrusion foaming, and is obtained by being extruded under atmospheric pressure through a circular slit of a die of an extruder, foamed, and sized into a cylindrical shape.

[0004]

However, since the conventional pipe-shaped foam formed by extrusion foaming is formed by extrusion foaming from a circular slit, there is a problem in molding. However, only limited ones, for example, those having a thickness of at most about 1 to 2 cm were obtained.

That is, to increase the thickness of the cylinder, a method of enlarging the gap between the circular slits of the die or a method of increasing the expansion ratio of the resin can be considered. However, any of these methods has a limit. In addition, a molded product having a certain thickness or more cannot be obtained.

For example, in the method of increasing the gap between the circular slits, if the gap is too large, it becomes difficult to maintain the resin pressure required for foaming, and foaming occurs in the mold before the resin is extruded from the slit. Starts and a good foaming state is not obtained. Regarding the method of increasing the expansion ratio of the foam, the expansion ratio is not less than a certain value (for example, 5%).
(About 0 times or more), it becomes impossible to control the size and shape, and a good foaming state cannot be obtained.

[0007] In addition, the above-mentioned pive-like foam made of an integral extruded foam molded article has substantially uniform elasticity including the inner and outer surfaces, so that the greater the thickness, the lower the flexibility. In addition, it is inferior in deformability when used as a pipe cover or the like.

The present invention has been made in view of the above, and a first object of the present invention is to provide a pipe-shaped foam which can be formed into a foam having a good foaming state inside and a large thickness. In addition, the present invention provides a pipe-shaped foam which is easy to achieve dimensional accuracy, has high elasticity and flexibility, and has good deformability in use.

Still another object of the present invention is to provide at least one skin layer on the inner and outer surfaces of a thermoplastic resin foam, in particular, a foam obtained by assembling a plurality of strips of the thermoplastic resin foam and partially fusing them. An object of the present invention is to provide a pipe-shaped foam having a high density and having a tensile strength and a tear strength.

[0010]

In order to solve the above-mentioned problems, a pipe-shaped foam of the present invention comprises a plurality of strips of a thermoplastic resin foam which are arranged in a plurality of layers in a ring shape to form voids continuous in the longitudinal direction. Is formed in a pipe shape by fusing at a portion adjacent to each strip so that the plurality of layers forming the plurality of layers are
From the outside to the outside, gradually decreasing the array density.
The gap formed by the fusion of
It is characterized by having.

It is particularly preferable that at least one of the inner and outer surfaces has a skin layer formed by a series of flattened strips having a higher density than other strips.

[0012]

According to the above-mentioned pipe-shaped foam of the present invention, since a plurality of strips of the thermoplastic resin foam are arranged in a ring shape in a plurality of layers and are fused at adjacent portions of each strip, The number of strips,
By appropriately setting the diameter, the number of layers, etc., it is possible to form a pipe of any thickness and size, and since each strip is foamed, good foaming even inside even if the thickness is large You get something in a state.

[0013] In particular, each strip which is arranged annularly a plurality of layers, because you are part to fuse adjacent portions so as to lie a gap continuous in the longitudinal direction, wherein the variation of the foam of the strip It is absorbed to some extent by the voids, and the control of the foaming state and the dimensions of the inner and outer diameters is facilitated, so that a pipe-shaped foam having a large thickness and high dimensional accuracy can be obtained.

In addition, since a continuous space in the longitudinal direction exists in the inside of the foam over the entire cross section, the foam as a whole must have elasticity and flexibility that can be obtained by the expansion ratio of the strip. Thus, even when the thickness is large, deformation such as bending is relatively easy.

Further, in the case of the present invention, a number of strips
From the side to the outside, gradually arrange the array density roughly,
The gap formed by the fusion of the strips is larger in the outer layer.
The elasticity and flexibility of the outer peripheral side
While the density increases, the density of the foam as a whole
And elasticity and strength are increased, and deformation such as bending occurs on the outside
And tensile strength and elasticity inside
It will be big. In the case where a skin layer formed by a series of flattened strips having a higher density than other strips is formed on at least one of the inner and outer surfaces, the high-density skin layer is reinforced. It acts as a layer, and retains moderately strong tensile and tear strength, even if each strip is partially fused so as to have voids inside as described above.

Particularly, when a high-density skin layer is provided on the inner surface,
The inner circumference is flattened like a normal integral foamed product,
For example, when used as a pipe cover, the adhesion to a pipe or the like is improved, and when a high-density skin layer is provided on the outer periphery, breakage or stripping of the strip due to contact with another object can be prevented.

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a pipe-like foam according to a first embodiment of the present invention, and FIGS.
And a pipe-like foam according to a third embodiment.

The pipe-shaped foam (A) of the first embodiment shown in FIG. 1 is composed of a plurality of flexible thermoplastic resin foams (1) having a substantially circular cross section and formed in parallel with a plurality of layers. And each strip (1) is fused at its adjacent portion to form a pipe having a circular cross section. In particular, the strip (1) of each layer is 3
Partially fused together at adjacent parts with light pressing so as to leave a void (2) with a polygonal cross section defined by more than one strip (1) and continuous in the longitudinal direction. Have been. (3) shows the fused portion.

The innermost strip (1) of the pipe-shaped foam (A) of this embodiment is formed in such a manner that adjacent strips (1) and (1) are fused to each other without being flattened to form an annular shape. Sedated,
In each of the outer layers, strips (1) having the same number and slightly larger diameter as the innermost strip (1) are arranged alternately sequentially with the inner strip (1) so that the adjacent strips are fused at each adjacent portion. It is formed so as to form a pipe as a whole.

As described above, by arranging the same number of the strips (1) in each layer alternately, each strip (1)
And the foaming state can be easily made uniform, and the dimensional accuracy of the inner and outer diameters of the cylinder can be easily obtained. In addition, by making the strips (1) of each layer approximately the same diameter, the array density of the strips (1) gradually becomes coarser from the inner side to the outer layer as shown in the figure, and The space (2) formed by fusion becomes larger toward the outside. That is, in the entire pipe-shaped foam (A), the porosity due to the voids (2) increases toward the outside, and the elasticity and flexibility of the outer layer increase.

In the pipe-shaped foam (A) of the second embodiment shown in FIGS. 2 and 3, the basic arrangement of a large number of strips (1) of each annular layer is the same as that of the above-described embodiment. It has voids (2) that are continuous in the longitudinal direction due to the fusion of the strips (1). In particular, the innermost layer is flattened and has a higher density than other strips (1), that is, a foam. Strips (1a) of the foam having a higher density than the entire density are continuously fused and formed in a ring shape to form a high-density skin layer (4), forming a substantially flat inner peripheral surface. .

Also in this embodiment, the number of the thin strips (1) of each layer except the innermost layer is made substantially the same in diameter and the same number, the arrangement density is made coarser from the inside to the outside, and the gap (2) is made closer to the outside. It is increasing gradually.

In the third embodiment shown in FIG.
In the same manner as in the second embodiment, the innermost layer is a skin layer (4) having a higher density than the others, and the outermost layer is also made of a foam having a higher density than the other strips (1) by flattening. Article (1
b) is formed as a skin layer (5) which is continuously fused and fused. The arrangement of the other strips (1) and the voids (2) are the same as in the above embodiment.

Although not shown, it is also possible to form only the outermost layer as a skin layer with a higher density strip as described above.

In each of the above embodiments, the strips (1) of each of the plurality of layers are arranged in substantially the same diameter and in substantially the same number, and the diameter, the number of the strips of each layer, the number of layers, etc. , Can be arbitrarily set according to the purpose of use, use, and the like. For example, as the outer layer, Ru it is possible to increase the number or increase the diameter of the strip (1). Further, the porosity of the entire pipe-shaped foam (A) due to the voids (2) is set to 3 to 50%, more preferably 5 to 30%, to maintain overall elasticity and flexibility. It is desirable from the viewpoint of integrity by fusing the strip.

As the thermoplastic resin used above, for example, a polystyrene resin such as a homopolymer or copolymer of polystyrene, a polyolefin resin such as a homopolymer or copolymer such as polyethylene or polypropylene, or a polyolefin resin such as A mixture of resins or other thermoplastic resins can be used. In particular, polyolefin resins such as polyethylene and polypropylene are preferably used from the viewpoint of flexibility.
Further, it goes without saying that, besides the foaming agent, a nucleating agent, a coloring agent, an antistatic agent and the like can be mixed with these resins as appropriate.

An example of a method for producing a pipe-shaped foam (A) from the above-mentioned thermoplastic resin foam strip (1) will be described.

For example, a thermoplastic resin such as polyethylene is supplied to an extruder. This extruder is provided with a die (12) as shown in FIG. 5, which is formed by arranging a large number of small holes (11) for extrusion in a plurality of concentric rings. Each of the small holes (11) of the die (12) is formed into a narrow strip (1) by extrusion foaming, and is pressed lightly through a sizing die. What is necessary is just to fuse and integrate each strip (1) so that the void (2) to be formed exists,
As a result, a cylindrical pipe-shaped foam is obtained.

In particular, by forming the small holes (11) of the base (12) to have substantially the same diameter and the same number as shown in FIG. 5 and sequentially and alternately forming them, the gap (2) gradually increases toward the outer layer. Thus, a pipe-shaped foam (A) of the illustrated embodiment is obtained. When the strips (1) having substantially the same diameter are formed as described above, the radial distance is reduced toward the outside.

The diameter of the small holes (11) varies depending on the diameter of the extruded and foamed strip (1) and the expansion ratio, but is usually 3/0 mm or less, preferably 0.5 to 2.5 m.
m.

When the innermost and / or outermost strips (1) are formed on the high-density skin layers (4) and (5), foaming is suppressed by sizing immediately after extrusion foaming. Is flattened, or the strip is flattened by utilizing shrinkage after foaming by natural cooling, thereby increasing the density of the strip itself.

For example, by forming the innermost layer strip (1) without cooling the inner peripheral portion, the innermost layer strip gradually shrinks after foaming and becomes flattened as shown in FIG. A dense skin layer (4) is formed. Needless to say, flattening by sizing enables formation with high dimensional accuracy.

In this extrusion foam molding, the number of each strip,
By appropriately setting the diameter, the number of layers, and the like, a pipe having an arbitrary thickness and size can be formed. Moreover, since each strip (1) is foamed and fused so as to have a gap, the variation in the foaming of the strip can be absorbed by the gap, and the foaming state and the dimensions of the inner and outer diameters can be easily controlled as a whole. Thus, a pipe-shaped foam having a large thickness and high dimensional accuracy can be obtained.

The diameter of the strip (1) formed by extrusion foaming as described above is preferably in the range of 1.0 mm to 10.0 mm. If the diameter is 1.0 mm or less, it is difficult to foam and fuse them.
Those having a thickness of 0 mm or more have a problem not only in that the surface becomes uneven and the appearance deteriorates, but also in terms of strength when used as a pipe cover or the like.

The shape of the strip obtained by extrusion foaming is not limited to a circular cross section as shown in the figure, but may be any cross sectional form such as a substantially square, substantially rectangular, polygonal or irregular shape. In the same manner as described above, a plurality of layers of annularly arranged strips are fused and integrated by gently pressing and fusing by sizing immediately after extrusion and foaming, and a pipe having a void inside. A foam can be obtained.

The cross-sectional form of the pipe-shaped foam (A) is not limited to a cylindrical pipe as in the illustrated embodiment, but may be an arbitrary pipe having a cross section of a square or polygon. It is possible. In this case, the arrangement of the small holes (11) for extruding the die (12) in the extruder may be changed as appropriate.

The pipe-like foam (A) produced as described above can be used for pipe covers for various pipes and other various uses. For example, when used as a pipe cover, as shown in FIG. 6, if a cut (7) is made in the longitudinal direction of the pipe-shaped foam (A) so that the pipe-shaped foam (A) can be opened and expanded, it can be used for attaching to a pipe or the like. Workability is improved. Further, it is particularly desirable in use that a synthetic resin film (8) is wound around the outer periphery as necessary and an adhesive portion (9) protected by release paper is provided.

The cuts (7) can be cut by a cutter after the molding, and at the time of molding, a part of the small holes (11) provided in the die (12) is closed. By doing so, it is possible to form the cut foam (7) into a shape in which the cut (7) is formed so as not to perform the fusion bonding at the portion.

Moreover, since the above-mentioned pipe-shaped foam (A) has voids (2) continuous in the longitudinal direction over the entire area of the cross section, the elasticity of the foam as a whole is higher than that obtained by the expansion ratio of the strip. It has flexibility and flexibility, and it is relatively easy to deform, such as bending, even if the thickness is large, and it is easy to adapt to the form of piping and the like.

As shown in FIG. 2 (FIG. 3), in the case where the skin layer (4) is formed on the inner surface by a series of flattened strips (1) having a higher density than the other strips (1). The high-density skin layer (4) serves as a reinforcing layer, and has a high tensile and tear strength even if it has voids (2) inside, and the inner periphery is formed of a normal integral foam molding. Since it is flattened like the product, the adhesion to a pipe or the like becomes good.

As shown in FIG. 4, when the outer surface also has a high-density skin layer (5), the skin layer (5) can prevent breakage and stripping of the strip due to contact with other objects, and is excellent in durability. Will be.

Example 1 A base having holes formed concentrically as shown in FIG. 5 was used. In other words, a total of 288 holes were formed with six bases provided with 48 holes having a diameter of 1.0 mm formed at equal intervals on the same circumference. The radius of each circumference is 23, 27, 31, 35, 38, 40 from the inside, respectively.
mm. Further, the holes formed in each circumference were arranged so as to be alternately positioned in each circumference. After the base, a Teflon cylinder having a diameter of 40 mm and a length of 100 mm is provided at the center as a sizing device.

As the resin, 100% by weight of a low-density polyethylene resin (manufactured by Mitsubishi Yuka Co., Ltd .: Yucalon ZK-30) is used as a base resin, and hydrocellol, which is a mixture of citric acid and sodium bicarbonate, is used as a cell regulator. 0.2 parts by weight of CF (manufactured by Boehringer Ingelheim) were previously mixed by a blender, and the mixture was supplied to a tandem extruder in which two units of 50 mm and 65 mm in diameter were connected.
The mixture supplied to the first extruder adjusted to 150 ° C. to 210 ° C. was melt-kneaded, and butane was injected as a foaming agent into the base resin at a rate of 12 parts by weight from the tip of the extruder. Thereafter, the mixture was introduced into the second extruder adjusted to 180 ° C. to 95 ° C., and the resin temperature was adjusted to a temperature suitable for foaming (about 105 ° C.), and the above-mentioned die maintained at 105 ° C. And extruded. The resin extruded from each hole of the die proceeds as a large number of foamed strips, and foamed and fused to each other during the process to obtain a pipe-shaped foam integrally formed.

The obtained foam had an inner diameter of 42 mm and an outer diameter of 9 mm.
At 0 mm, the density of about 3 mm at the innermost circumference of the foam is 0.096 g / cc, the density of the remaining outer portion is 0.033 g / cc, and the density of the entire foam is 0.038 g / cc. Met. Further, the voids became larger toward the outer periphery of the foam, and the foam was rich in flexibility and cushioning properties.

Example 2 The procedure of Example 1 was followed, except that a polypropylene resin was used as the resin. 0.2% by weight of hydrocerol HK (manufactured by Boehringer Ingelheim), which is a mixture of citric acid and sodium bicarbonate as a foam control agent, with 100% by weight of polypropylene resin (manufactured by Himont: SD632) as a base resin. Was previously mixed in a blender, and the mixture was supplied to a tandem extruder in which two units of 50 mm and 65 mm in diameter were connected. 150 ° C to 230 ° C
The mixture supplied to the first extruder was melt-kneaded, and butane as a foaming agent was pressed into the base resin at a rate of 10 parts by weight from the tip of the extruder. afterwards,
The mixture is then introduced into a second extruder adjusted to 180 ° C. to 145 ° C., and a temperature suitable for foaming (about 158 ° C.)
The resin temperature was adjusted and extruded with the same die as in Example 1 kept at 158 ° C. The resin extruded from each hole of the die proceeds as a large number of foamed strips, and during that time, foamed and fused to each other to obtain an integrated pipe-shaped foam.

The obtained foam had an inner diameter of 44 mm and an outer diameter of 8 mm.
0 mm, thickness 18 mm, innermost layer density 0.095
g / cc, and the density of the remaining part outside the area of 0.041
g / cc, density of the whole foam is 0.045 g / c
c.

[0048]

As described above, the pipe-shaped foam according to the present invention is obtained by arranging a plurality of strips of a thermoplastic resin foam in a ring shape in a plurality of layers and fusing the strips adjacent to each strip. for,
Unlike extruded foam molding of the whole, it can be a foam with good foaming to the inside and a large thickness, and it is easy to obtain dimensional accuracy of inner and outer diameters, and good quality pipe-shaped foam Can be obtained.

Moreover, since the pipe-shaped foam of the present invention has voids continuous in the longitudinal direction inside the entire cross-section, elasticity and flexibility higher than those obtained by the expansion ratio of the strip as a whole foam can be obtained. Therefore, even if the thickness is large, deformation such as bending becomes relatively easy.

In particular, it is formed by fusing said strips.
The outer layer has larger elasticity, so the outer layer has elasticity.
And the flexibility increases, while the inner peripheral side
Density and elasticity and strength increase,
It can be particularly suitably used as a cover cover or the like. Furthermore, as in the invention of claim 2, when a skin layer is formed on at least one of the inner and outer surfaces by a series of flattened strips,
This high-density skin layer serves as a reinforcing layer, and has a space inside as described above, is flexible, and has a moderately high tensile and tear strength.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of the same.

FIG. 4 is a cross-sectional view showing still another embodiment of the present invention.

FIG. 5 is a front view of a die used for molding according to the present invention.

FIG. 6 is a perspective view when a pipe-shaped foam is used for a pipe cover.

[Explanation of symbols]

 (A) Pipe-like foam (1) Strip (1a) (1b) Flattened strip (2) Void (3) Fused portion (4) Inner skin layer (5) Outer skin layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification symbol FI // B29K 105: 04 B29L 23:00 B29L 23:00 B29C 67/22 (58) Fields surveyed (Int.Cl. ⁷ , DB Name) B29C 47/00-47/96 B29C 67/22 B32B 1/08 B32B 5/18 B32B 5/32

Claims (2)

(57) [Claims] A plurality of thermoplastic resin foam strips are arranged in a ring shape in a plurality of layers, and are formed into a pipe shape by fusing at adjacent portions of the strips so as to have voids continuous in the longitudinal direction. Become
Numerous strips in multiple layers progressively from inside to outside
Arranged with coarse array density, formed by fusing thin strips
A pipe-shaped foam, wherein voids formed are larger in an outer layer . 2. A pipe-like structure according to claim 1, wherein a skin layer is formed on at least one of the inner and outer surfaces by a series of flattened strips having a higher density than other strips. Foam.