JPH08156001A - Pipe-like foam - Google Patents

Abstract

PURPOSE: To obtain a pipe-like foam which has a large thickness in a satisfactory foaming condition way deep into the core, can be formed easily to highly precise dimensions, and is highly responsive to any deforming requirement in use with outstanding elasticity and flexibility. CONSTITUTION: This pipe-like foam comprises annularly arranged layers of strips of a thermoplastic resin foam, with the adjacent part of each strip fused in a pipe shape so that voids 2 which are continuous in a longitudinal direction are present. In addition, a skin layer 4 comprising continuous flat strips 1a of higher density than the other strips 1 are formed at least, on one of the inner or outer surface. Further, layers of plural stripe 1 are arranged in such a manner that their arrangement density becomes gradually lower from inside to outside, and the voids 2 formed by fusion of the strips 1 become larger toward the outer layers.

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 an annular cross section formed by fusing a plurality of thermoplastic resin foams at adjacent portions.

[0002]

2. Description of the Related Art For example, as a so-called pipe cover which is attached to pipes for supplying water or hot water, pipes for cooling and heating, and other pipes for the purpose of heat insulation and buffer protection, a flexible synthetic material formed into a cylindrical shape. Resin foam (that is, pipe-shaped foam) is generally used. Further, this pipe-shaped foam is also used as a cushioning material or a protective material for other articles such as wood.

Conventionally, many pipe-shaped foams of this type are formed by extrusion foaming, and are extruded from the circular slit of the die of an extruder under atmospheric pressure to foam, and are sized into a cylindrical shape.

[0004]

However, the conventional pipe-shaped foam produced by extrusion foam molding has a problem in molding since it is produced by extrusion foam molding from a circular slit, and therefore there is a problem in size and thickness. It was possible to obtain only a limited one, for example, a thickness of at most 1 to 2 cm.

That is, in order to increase the thickness of the cylinder, a method of increasing the gap between the circular slits of the die or a method of increasing the foaming ratio of the resin can be considered, but there is a limit in any of these methods. However, a molded product having a certain thickness or more cannot be obtained.

For example, in the case of the method of increasing the gap of the circular slit, if the gap is too large, it becomes difficult to maintain the resin pressure required for foaming, and the resin is foamed in the mold before being extruded from the slit. Starts and the foaming state does not become good. In addition, regarding the method of increasing the expansion ratio of the foam, the expansion ratio is not less than a certain level (for example, 5
If it is about 0 times or more), it becomes impossible to control the size and shape, and a good foaming state cannot be obtained.

In addition, since the above-mentioned pebble foam made of the integral extrusion foam-molded product has substantially uniform elasticity over the entire inner and outer surfaces, the greater the thickness, the lower the flexibility. Therefore, it is inferior in deformability in use 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 foamed body having a good foaming state up to the inside and a large thickness. In addition, the present invention provides a pipe-shaped foam which is easy to obtain dimensional accuracy, has high elasticity and flexibility, and has good adaptability to deformation during use.

Still another object of the present invention is to provide at least one of the skin layers on the inner and outer surfaces of a foamed product in which a large number of strips of thermoplastic resin foam are gathered and partially fused. It is an object of the present invention to provide a pipe-shaped foam which has a high density and has tensile strength and tear strength.

[0010]

In the pipe-shaped foam of the present invention for solving the above-mentioned problems, a large number of strips of a thermoplastic resin foam are arranged in a plurality of layers in an annular shape, and voids continuous in the longitudinal direction are formed. It is characterized in that it is formed in a pipe shape by being fused at the adjacent portions of the respective strips as it exists.

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

Further, the plurality of strips forming the above-mentioned plurality of layers are arranged from the inner side toward the outer side so that the arrangement density is gradually roughened.
It is more preferable that the voids formed by fusion bonding of the strips become larger in the outer layer.

[0013]

According to the above-mentioned pipe-shaped foam of the present invention, since a large number of strips of the thermoplastic resin foam are arranged in a plurality of layers in an annular shape and are fused at the adjacent portions of the strips, Number of strips,
By appropriately setting the diameter, number of layers, etc., it can be formed into a pipe shape of any thickness and size, and since it is foamed in each strip, even if the thickness is large, good foaming to the inside The one in the state is obtained.

In particular, since the plurality of strip-shaped strips arranged in an annular shape are partially fused at adjacent portions so that there are continuous voids in the longitudinal direction, variations in foaming of the strips are caused by the gaps. Is absorbed to some extent, the foamed state and the dimensions of the inner and outer diameters are easily controlled, and a pipe-shaped foam having a large thickness and high dimensional accuracy can be obtained.

In addition, since voids continuous in the longitudinal direction are present inside the foam throughout the entire cross section, the foam as a whole should have elasticity and flexibility greater than that obtained by the expansion ratio of the strip. Therefore, even if the thickness is large, deformation such as bending is relatively easy.

Further, when 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 the other strips, the high-density skin is provided. The layer functions as a reinforcing layer, and even if the strips are partially fused so as to have voids inside as described above, they have moderately strong tensile and tear strengths.

Particularly when the inner surface has a high-density skin layer,
The inner circumference is flattened like a normal one-piece foam molded product,
For example, when it is used as a pipe cover, it has good adhesion to pipes and the like, and when it has a high-density skin layer on the outer circumference, it is possible to prevent breakage and stripping of strips due to contact with other objects.

Further, as claimed in claim 3, a large number of strips are arranged from the inner side toward the outer side so that the arrangement density is gradually roughened, and the voids formed by fusion bonding of the strips are closer to the outer layer. When it is increased, the elasticity and flexibility on the outer peripheral side are increased, while the density of the foam as a whole is increased toward the inner peripheral side to increase the elastic force and strength, and the outer side is easily deformed by bending and the like. Inside, the tensile strength and elastic force are large.

[0019]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 shows a pipe-shaped foam according to the first embodiment of the present invention, and FIG. 2, FIG. 3 and FIG.
And the pipe-shaped foam of the third embodiment.

In the pipe-shaped foam (A) of the first embodiment shown in FIG. 1, a large number of strips (1) of a flexible thermoplastic resin foam having a substantially circular cross section are arranged in parallel in a plurality of layers. And the strips (1) are fused at their adjacent portions to form a pipe shape having a circular cross section. In particular, the number of strips (1) in each layer is 3
Partly fused and integrated at adjacent parts while being lightly pressed so that a void (2) having a polygonal cross section continuous in the longitudinal direction defined by the above-mentioned thin strips (1) is left Has been done. (3) shows the fused portion.

The strips (1) of the innermost layer of the pipe-shaped foam (A) of this example are continuous in an annular shape by adhering the strips (1) (1) adjacent to each other without flattening. Confused,
In each of the outer layers, the same number of strips (1) as the innermost strip (1) and having a slightly larger diameter are arranged alternately in a staggered manner with the inner strips (1) so that the adjacent strips are fused at each adjacent portion. It is worn and formed into a pipe shape as a whole.

By staggering the same number of strips (1) in each layer as described above, each strip (1) is
The arrangement is well balanced, the foaming state is easily made uniform, and the dimensional accuracy of the inner and outer diameters of the cylinder is easily obtained. Further, by making the strips (1) of each layer have substantially the same diameter, the arrangement density of the strips (1) gradually becomes coarser from the inner side toward the outer layer as shown in the figure, so that the strips (1) are The void (2) formed by fusion is larger toward the outside. That is, in the pipe-shaped foam (A) as a whole, the porosity of the voids (2) increases toward the outside, and the elasticity and flexibility of the outer layer increase.

In addition, 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-mentioned embodiment. It has voids (2) continuous in the longitudinal direction by fusing the strips (1), and in particular, the innermost layer thereof is flattened and has a higher density than the other strips (1), that is, a foam. The foam strips (1a) having a higher density than the overall density are fused and continuous in an annular shape to form a high-density skin layer (4), which forms a substantially flat inner peripheral surface. .

Also in this embodiment, a large number of strips (1) of each layer except the innermost layer are made to have substantially the same diameter and the same number, and the array density is roughened from the inner side to the outer side, and the voids (2) are closer to the outer side. It is gradually increasing.

Further, in the third embodiment shown in FIG.
In addition to forming the innermost layer with a higher density skin layer (4) as in the second embodiment, the outermost layer is also flattened so that it has a density higher than that of the other strips (1). Article (1
b) is formed as a skin layer (5) that is fused and continuous in an annular shape. The arrangement configuration of the other strips (1) and the voids (2) are the same as in the above embodiment.

Although not shown, it is possible to form only the outermost layer as a skin layer having a higher density than that of the others as described above.

In each of the above-mentioned embodiments, the strips (1) of each of the plurality of layers have the same diameter and the same number of arrangements, as well as the diameter, the number and the number of strips of each layer. , And can be arbitrarily set according to the purpose of use or the purpose of use. For example, it is possible to increase the diameter of the strips (1) or increase the number of strips in the outer layer, and in some cases, increase the porosity of the voids (2) in the inner layer.

The void ratio (2) of the entire pipe-shaped foam (A) is 3 to 50%, more preferably 5%.
It is desirable to set it to -30% from the viewpoint of maintaining the overall elasticity and flexibility, and the integrity by fusing the respective fine lines.

Examples of the thermoplastic resin used above include polystyrene resins such as polystyrene homopolymers and copolymers, polyolefin resins such as polyethylene and polypropylene homopolymers and copolymers, or these resins. Mixtures of resins and other thermoplastic resins can be used. In particular, polyolefin resins such as polyethylene and polypropylene are preferably used from the viewpoint of flexibility.
Needless to say, in addition to the foaming agent, a nucleating agent, a coloring agent, an antistatic agent, etc. can be appropriately mixed with these resins.

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

For example, a thermoplastic resin such as polyethylene is supplied to the extruder. The extruder is equipped 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 concentric annular shape in a plurality of rows. Then, extrusion molding is performed from the large number of small holes (11) of the die (12) into strips (1) respectively, and the strips are lightly pressed through a sizing die so that three or more strips (1) are formed. The strips (1) may be fused and integrated with each other so that the voids (2) formed are present,
This gives a cylindrical pipe-shaped foam.

In particular, by forming the small holes (11) of the die (12) in a staggered order with substantially the same diameter and the same number as shown in FIG. 5, the outer layer has a gradually larger void (2). The pipe-shaped foam (A) of the illustrated embodiment is obtained. When the strips (1) having substantially the same diameter are formed in this way, the radial distance is made smaller toward the outer side.

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

When the strips (1) of the innermost layer and / or the outermost layer are formed in the high-density skin layers (4) and (5), foaming is suppressed by sizing immediately after extrusion foaming, and the strips are suppressed. Or flattening the strips by utilizing shrinkage after foaming due to natural cooling so that the strips themselves have a high density.

For example, by forming the innermost strip (1) without cooling the inner peripheral portion thereof, the innermost strip is gradually shrunk after foaming and flattened as shown in FIG. A dense skin layer (4) is formed. Of course, flattening by sizing allows for more accurate dimensional formation.

In this extrusion foam molding, the number of each strip,
By appropriately setting the diameter, the number of layers, etc., it is possible to form a pipe having an arbitrary thickness and size. In addition, since each thin strip (1) is foamed and fused so that there are voids, variations in foaming of the strips can be absorbed by the voids, and the overall foaming state and inner and outer diameter dimensions can be easily controlled. It is possible to obtain a pipe-shaped foam having a large thickness and high dimensional accuracy.

The diameter of the strip (1) extruded and foamed 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 becomes difficult to form by foaming and fusing.
If the thickness is 0 mm or more, not only the surface becomes uneven and the appearance deteriorates, but also there is a problem in strength when used as a pipe cover or the like.

Further, the shape of the strip obtained by extrusion foam molding is not limited to the one having a circular cross section as shown in the figure, but any cross sectional shape such as a cross section having a substantially square shape, a substantially rectangular shape, a polygonal shape, or an amorphous shape. In the same manner as above, by lightly pressing and fusing by sizing immediately after extrusion foaming, a plurality of strips arranged in an annular shape are fused and integrated, and a pipe having a void inside is formed. Foam can be obtained.

Further, the cross-sectional form of the pipe-shaped foam (A) may be a cylindrical pipe like the illustrated embodiment, or may be an arbitrary pipe such as a square or polygonal cross section. It is possible. In this case, the arrangement of the small holes (11) for extruding the die (12) in the above extruder may be changed appropriately.

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

The notch (7) may be formed by a cutter after molding, or at the time of molding, a part of the small holes (11) arranged in the die (12) may be closed. It is also possible to form the notched portion (7) in the formed foam body so as not to be fusion-bonded at that portion.

In addition, since the pipe-shaped foam (A) has the voids (2) continuous in the longitudinal direction over the entire cross section, the elasticity of the entire foam is more than that obtained by the expansion ratio of the strip. Since it has flexibility and flexibility, it is relatively easy to be deformed such as bending even if it has a large thickness, and it is easy to adapt it to the form of piping or the like.

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

Further, as shown in FIG. 4, when the outer surface also has a high-density skin layer (5), the skin layer (5) can prevent damages and strips of strips due to contact with other objects, and have excellent durability. It will be.

Example 1 As the die, a die provided with holes on concentric circles as shown in FIG. 5 was used. That is, a total of 288 holes are formed by a die having six holes each having 48 holes of 1.0 mm in diameter formed at equal intervals on the same circumference. The radius of each circumference is 23, 27, 31, 35, 38, 40 from the inside.
mm. Furthermore, the holes formed in each circumference were arranged so that they would be staggered for each circumference. After the base, a Teflon cylinder having a diameter of 40 mm and a length of 100 mm is provided in the center as a sizing device.

As the resin, 100% by weight of a low-density polyethylene resin (Yukaron ZK-30 manufactured by Mitsubishi Petrochemical Co., Ltd.) was used as a base resin, and hydrocelol, which is a mixture of citric acid and sodium bicarbonate as a bubble control agent, was used as the base resin. 0.2 parts by weight of CF (Boehringer Ingelheim) was mixed in advance with a blender, and the mixture was supplied to a tandem extruder in which two units having a diameter of 50 mm and a diameter of 65 mm were connected.
The mixture supplied to the first extruder adjusted to 150 ° C to 210 ° C was melt-kneaded, and butane as a foaming agent was pressed into the base resin at a ratio of 12 parts by weight from the tip of the extruder. After that, the mixture was introduced into a second extruder which was then adjusted to 180 ° C to 95 ° C, the resin temperature was adjusted to a temperature suitable for foaming (about 105 ° C), and the above-mentioned spinneret kept at 105 ° C was adjusted. Was extruded. The resin extruded from each hole of the die progressed as a large number of foamed thin strips, and during that time, foamed and fused to each other to obtain an integrated pipe-shaped foam.

The obtained foam has an inner diameter of 42 mm and an outer diameter of 9
At 0 mm, the density of the innermost layer of the foam, which is about 3 mm, is 0.096 g / cc, the density of the remaining outer portion is 0.033 g / cc, and the density of the foam as a whole is 0.038 g / cc. Met. Further, the voids became larger toward the outer periphery of the foam, and the foam had excellent flexibility and cushioning properties.

Example 2 The procedure of Example 1 was followed, but using a polypropylene resin as the resin. 0.2 parts by weight of Hydrocerol HK (made by Boehringer Ingelheim), which is a mixture of citric acid and sodium bicarbonate as a foam control agent, using 100% by weight of polypropylene resin (SD632 made by Highmont) as a base resin. Was mixed in advance with a blender, and the mixture was supplied to a tandem extruder in which two units having a diameter of 50 mm and a diameter of 65 mm were connected. 150 ℃ ~ 230 ℃
The mixture supplied to the first extruder adjusted to 1 was melt-kneaded, and butane as a foaming agent was pressed into the base resin at a ratio of 10 parts by weight from the tip of the extruder. afterwards,
The mixture is then introduced into a second extruder, which is regulated at 180 ° C to 145 ° C, at a temperature suitable for foaming (about 158 ° C).
The resin temperature was adjusted to 1, and extrusion was performed using the same die as in Example 1 kept at 158 ° C. The resin extruded from each hole of the die progressed in the form of a large number of foamed strips, and in the meanwhile, foamed and fused to each other to obtain an integral pipe-shaped foam.

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

[0051]

As described above, the pipe-shaped foam of the present invention is formed by arranging a large number of strips of a thermoplastic resin foam in an annular shape of a plurality of layers and fusing the strips adjacent to each other. for,
Unlike extrusion foam molding of the whole as a whole, it is possible to make a foam with a good foaming state to the inside and a large thickness, and it is easy to give dimensional accuracy of the inner and outer diameters, and a 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, the elasticity and flexibility of the foam as a whole are greater than those obtained by the expansion ratio of the strip. Therefore, even if the thickness is large, deformation such as bending is relatively easy.

Further, as in the invention of claim 2, when a skin layer formed by continuous flattened strips is formed on at least one of the inner and outer surfaces, the high-density skin layer serves as a reinforcing layer. In addition, as described above, it has voids inside, is flexible, and has moderately strong tensile and tear strengths.

Further, as in the invention of claim 3, when the voids formed by the fusion of the strips are made larger toward the outer layer,
While the elasticity and flexibility on the outer peripheral side are increased, the density of the foam as a whole becomes higher toward the inner peripheral side to increase the elastic force and strength, and thus it can be particularly suitably used as a pipe cover or the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an 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 of 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-shaped foam (1) Strips (1a) (1b) Flattened strips (2) Voids (3) Fused parts (4) Inner skin layer (5) Outer skin layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location // B29K 105: 04 B29L 23:22

Claims (3)

[Claims] 1. A large number of strips of a thermoplastic resin foam are arranged in a plurality of layers in an annular shape, and are fused at adjacent portions of the strips to form a pipe shape so as to have continuous voids in the longitudinal direction. A pipe-shaped foam body characterized by the following. 2. The pipe shape according to claim 1, wherein at least one of the inner and outer surfaces is formed with a skin layer formed by continuous flattened strips having a higher density than other strips. Foam. 3. A plurality of strips forming a plurality of layers are arranged from the inner side to the outer side so that the arrangement density gradually becomes coarser, and the voids formed by fusing the strips are larger in the outer layer. The pipe-shaped foam according to claim 1 or 2.