WO2018123090A1

WO2018123090A1 - Foamed resin tube manufacturing device and manufacturing method, and foamed resin tube

Info

Publication number: WO2018123090A1
Application number: PCT/JP2017/011472
Authority: WO
Inventors: 良治菊澤
Original assignee: 株式会社プラ技研
Priority date: 2016-12-27
Filing date: 2017-03-22
Publication date: 2018-07-05
Also published as: JP6411700B1; WO2018124213A1; JPWO2018124213A1; JPWO2018123090A1

Abstract

Provided are a foamed resin tube manufacturing device and manufacturing method with which it is possible to manufacture, in the smaller number of steps and at a higher yield, a foamed resin tube having a surface provided with protrusions and recesses by embossing while suppressing distortion of the cross-sectional shape. A die 2 is provided with a ring-shaped first discharge port 33 and a first channel 35 communicating with the first discharge port 33. The first channel 35 in the die 2 is supplied with a first resin in a melted state containing a foaming agent from a first resin supply unit. The first discharge port 33 in the die 2 is disposed in a molding space sandwiched by concave portions of a mold 20a and a mold to be paired with the mold 20a. Vacuum molding or air pressure molding is performed in a molding device 5 while pushing the first resin containing the foaming agent out from the first discharge port 33, whereby the foaming of the first resin and the molding of the first resin into a tubular shape having a surface with emboss design can be simultaneously performed.

Description

Foamed resin tube manufacturing apparatus and method, foamed resin tube

The present invention relates to a foamed resin tube manufacturing apparatus and manufacturing method used as a heat insulating material for piping, and a foamed resin tube.

Conventionally, a foamed resin tube made of a resin foam obtained by foaming a resin such as cross-linked polyethylene has been widely used as a heat insulating material (insulating cover) for piping. In this foamed resin tube, when it is attached to the outer surface of the bent part of the piping, the generation of wrinkles is suppressed to improve the aesthetic appearance, the bendability is increased to reduce friction during installation, and as a non-slip Some have their surface embossed for functional purposes.

FIG. 6 is a cross-sectional view showing a conventional method for manufacturing an embossed foamed resin tube, and FIG. 7 is a perspective view of a part of the conventional embossed foamed resin tube manufactured by the manufacturing method of FIG.

First, as shown in FIG. 6A, a flat resin foam 81 formed by foaming a resin such as cross-linked polyethylene is prepared, and a film 82 made of a thermoplastic resin is overlaid on the surface. Next, in a state where the surfaces of the film 82 and the resin foam 81 are heated and softened, an embossing roll having irregularities formed on the surface is used to perform an embossing process, as shown in FIG. Then, the uneven layer 83 in which the uneven shape of the embossing roll is transferred to the surface of the resin foam 81 is formed. The embossed resin foam 81 is cut into a strip shape having a width corresponding to the diameter of the foamed resin tube to be formed. Next, as shown in FIG. 6 (c), the cut strip-shaped resin foam 81 is rounded into a cylindrical shape so that the uneven layer 83 is on the outside, and the end faces 84a and 84b of the resin foam 81 are heated and melted. Then, as shown in FIG. 6D, the end faces 84a and 84b are butted and joined. 6A and 7B, the foamed resin tube 80 in which the uneven layer 83 by embossing is formed on the surface of the tubular resin foam 81 is completed.

In addition, in the foamed resin tube manufactured by the manufacturing method shown in FIG. 6, a joint portion 85 in which the end faces of the flat resin foam are joined appears (broken line portions in FIG. 6E and FIG. 7).

Japanese Examined Patent Publication No. 47-46463 JP-A-9-314661

In the conventional manufacturing method described above, a foamed resin tube is manufactured by using a flat resin foam as a material, rounding it into a cylindrical shape, and heat-sealing the end faces. Although there is a difference in circumference between the inner and outer circumferences of the foamed resin tube, the resin foam in the inner circumference side of the foamed resin tube is rounded into a cylindrical shape because the band-shaped resin foam before heat sealing has a certain width. The body will be compressed. For this reason, a stress difference is generated between the inner peripheral side and the outer peripheral side of the foamed resin tube, and the cross-sectional shape of the foamed resin tube becomes a distorted shape instead of a perfect circle due to the stress difference. If the cross-sectional shape of the foamed resin tube is distorted, it is not preferable in terms of aesthetics.

Further, the above-described conventional manufacturing method has a problem that the manufacturing apparatus becomes complicated and the manufacturing cost increases because the number of manufacturing steps is large. In addition, since the flat resin foam is cut into a strip shape in accordance with the pipe diameter of the pipe, if the end material is generated, the yield is lowered and the manufacturing cost is increased.

Therefore, the present invention provides a foamed resin tube manufacturing apparatus and a manufacturing method capable of manufacturing a foamed resin tube having an uneven surface formed by embossing on the surface while suppressing distortion of a cross-sectional shape with a small number of steps and high yield. For the purpose. Another object of the present invention is to provide a foamed resin tube with less cross-sectional distortion.

The present invention relates to an apparatus for producing a foamed resin tube having an embossed pattern on the surface. The foamed resin tube manufacturing apparatus includes a die having an annular first discharge port, a first flow path communicating with the first discharge port, and a thermoplastic first resin by melting and kneading the molten first resin. A first resin supply unit that mixes the foaming agent with the first flow path and supplies the first flow path to the first flow path of the die, and a plurality of first molds having a recess corresponding to a part of the outer surface shape of the foamed resin tube The first resin discharged from the first discharge port of the die is formed by vacuum molding or pressure molding with air using a plurality of second molds having concave portions corresponding to the other part of the shape. And a molding device for forming an embossed pattern while forming into a tubular shape. The first discharge port of the die is disposed in a molding space sandwiched between the concave portion of the first mold and the concave portion of the second mold.

The present invention also relates to a method for producing a foamed resin tube having an embossed pattern on the surface, the first mold having a recess corresponding to a part of the outer surface shape of the foamed resin tube, and the outer surface shape of the foamed resin tube. A melt containing a foaming agent in a molding space sandwiched between a recess of the first mold and a recess of the second mold, using a second mold having a recess corresponding to the other part of the mold The extruded first thermoplastic resin is extruded from the annular first discharge port provided in the die into a tubular shape, and is subjected to vacuum molding or pressure molding with air, thereby discharging the first resin discharged from the first discharge port of the die. 1 resin is molded into a tube and an embossed pattern is formed.

Further, the present invention relates to a foamed resin tube having an embossed pattern on the surface, and is characterized in that it has an integral tube shape with no welding marks in a cross section perpendicular to the longitudinal direction.

According to the present invention, it is possible to provide a foamed resin tube manufacturing apparatus and a manufacturing method capable of manufacturing a foamed resin tube having an uneven surface by embossing on the surface while suppressing distortion of the cross-sectional shape and with a small number of processes. Moreover, according to this invention, the foamed resin tube with few distortion of a cross-sectional shape can be provided.

FIG. 1 is a schematic diagram illustrating a foamed resin tube manufacturing apparatus according to an embodiment. FIG. 2 is a partially enlarged view of the molding apparatus and die shown in FIG. FIG. 3 is a cross-sectional view taken along line III-III shown in FIG. FIG. 4 is an enlarged cross-sectional view of the die shown in FIG. FIG. 5 is a perspective view of a part of the foamed resin tube manufactured by the manufacturing apparatus according to the embodiment. FIG. 6 is a cross-sectional view showing a conventional method for producing an embossed foamed resin tube. FIG. 7 is a perspective view of a part of a conventional embossed foamed resin tube manufactured by the manufacturing method of FIG.

FIG. 1 is a schematic view showing a foamed resin tube manufacturing apparatus according to an embodiment.

The foamed resin tube manufacturing apparatus 1 supplies an extrusion molding die 2 for extruding the first resin and the second resin, a first resin extrusion unit 3 for supplying the first resin to the die 2, and supplying the second resin to the die 2. A second resin extruding portion 4 that molds the resin extruded from the die 2 into a tubular shape, and a molding device 5 that transfers the embossed shape to the surface.

The die 2 is a tubular mold having a triple structure, and an annular first discharge port for extruding the first resin that becomes a foam and an annular that extrudes the second resin that becomes a resin film covering the surface of the foam. A second discharge port. Connected to the die 2 are a first resin extruding part 3 for supplying a first resin and a second resin extruding part 4 for supplying a second resin. Details of the structure of the die 2 will be described later.

The 1st resin extrusion part 3 is equipped with

extruder

11a and 11b and the communication path 15 which makes these communicate.

The extruder 11a includes a hopper (not shown) for charging the first resin pellets, a housing 13a having a screw therein and melting the resin therein, and a motor 14a for rotating the screw in the housing 13a. Is provided. The extruder 11a is provided with a heater (not shown) for heating the resin inside the housing 13a. An injection port 18 is provided in an intermediate portion in the longitudinal direction of the housing 13a, and a foaming agent is injected into the housing through the injection port 18. The extruder 11 a mixes the foaming agent injected from the injection port 18 with the melted first resin, and supplies the first resin mixed with the foaming agent into the housing 13 b of the extruder 11 b through the communication path 15.

The extruder 11b includes a housing 13b having a screw for kneading the molten resin therein, and a motor 14b for rotating the screw in the housing 13b. The extruder 11b is provided with a heater (not shown) for heating the resin inside the housing 13b. The temperature in the housing 13b is set lower than the temperature in the housing 13a of the extruder 11a, and the first resin is cooled to a predetermined temperature in the course of being kneaded in the housing 13b. By the cooling and kneading by the extruder 11b, the foaming agent is uniformly dispersed between the molecules of the first resin. The extruder 11b supplies the cooled first resin to the flow path communicating with the first discharge port provided in the die 2.

The first resin is not particularly limited as long as it is a foamable thermoplastic resin, but polyurethane, polystyrene, polyethylene, crosslinked polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene-propylene copolymer, polyethylene terephthalate, Polyvinyl chloride, nylon, etc. can be used. As the foaming agent, hydrocarbons such as butane and pentane, and inert gases such as carbon dioxide and nitrogen can be used. For use as a heat insulating material for piping, crosslinked polyethylene is preferable as the first resin, and in this case, butane, pentane, or the like is preferable as the foaming agent. In addition, when cross-linked polyethylene is used as the first resin, the kneading temperature in the extruder 11a is preferably around 180 ° C., and the kneading temperature in the extruder 11b is preferably 100 to 120 ° C.

The second resin extrusion unit 4 is composed of an extruder 12. The extruder 12 includes a hopper (not shown) for charging the pellets of the second resin, a housing 16 having a screw therein, and a motor 17 for rotating the screw in the housing 16. Further, the extruder 12 is provided with a heater (not shown) for heating the resin inside the housing 16. The extruder 12 melts and kneads the first resin introduced from the hopper in the housing 16 and supplies the melted second resin to the flow path communicating with the second discharge port provided in the die 2.

The second resin is not particularly limited as long as it is a thermoplastic resin. Polyurethane, polystyrene, polyethylene, crosslinked polyethylene, polypropylene, ethylene vinyl acetate copolymer, ethylene-propylene copolymer, polyethylene terephthalate, polyvinyl chloride, nylon Etc. can be used. Among these, polyolefin resins such as polyethylene, cross-linked polyethylene, polypropylene, and ethylene-propylene copolymer can be suitably used.

The molding apparatus 5 is an apparatus for continuously molding a resin tube (resin pipe) having irregularities on its surface by using a plurality of pairs of

molds

20a and 20b divided into two. The molding device 5 may be called a corrugator that continuously molds a long corrugated pipe. By changing the shape and size of the recesses of the

molds

20a and 20b used in the molding apparatus 5, foamed resin tubes having various diameters or various embossed patterns can be molded. The resin tube is molded by the molding apparatus 5 by vacuum molding in which the pores provided in the mold are vacuum-sucked, and by air being blown into the center of the mold and pressurized. Although there is pressure molding, any method may be adopted. Details of the molding of the resin tube in the molding apparatus 5 will be described later.

A cooling device 6 that cools the molded foamed resin tube 10, a take-up device 7 that takes up the foamed resin tube 10, and a winding device 8 that winds up the foamed resin tube 10 are sequentially provided downstream of the molding device 5. ing.

FIG. 2 is a partially enlarged view of the molding apparatus and die shown in FIG. 2, and FIG. 3 is a cross-sectional view taken along the line III-III shown in FIG. FIG. 4 is an enlarged cross-sectional view of the die shown in FIG.

2, the molding apparatus 5 includes a plurality of pairs of

molds

20a and 20b divided into two. Each mold 20a is transported in the direction of the block arrow in FIG. 2 by the transport mechanism 22a and circulates along the transport path 21a. Similarly, each mold 20b is transported in the direction of the block arrow in FIG. 2 by the transport mechanism 22b and circulates along the transport path 21b. Each of the

molds

20a and 20b is formed with a substantially semi-cylindrical recess for molding a part of the predetermined length of the foamed resin tube in the circumferential direction. In addition, as shown by shading in FIG. 3, the surface of the recess formed in the mold 20a is provided with unevenness (an embossed pattern reversal pattern) to be transferred to the surface of the resin tube. Although not shown in the drawings, the concave portion of the mold 20b is similarly provided with unevenness (an embossed pattern reversal pattern) to be transferred to the surface of the resin tube.

2 and 3, when the pair of

molds

20a and 20b are on a straight conveyance path parallel to the central axis of the die 2, the divided

surfaces

23a and 23b come into contact with each other. Further, on the linear conveyance path, a pair of

molds

20a and 20b in which the split surfaces 23a and 23b are in contact with each other are connected along the linear conveyance path (in a direction parallel to the central axis of the die 2). In a plurality of pairs of

molds

20a and 20b adjacent to each other in the conveyance path direction, a substantially cylindrical molding space corresponding to the outer shape of the foam resin tube having a predetermined length is formed.

3 and 4, the die 2 includes a mandrel 30, a tubular die 31 that surrounds the outside of the mandrel 31, and a tubular die 32 that surrounds the outside of the die 31.

A first flow path 35 is formed between the outer peripheral surface of the mandrel 30 and the inner peripheral surface of the die 31 with a predetermined gap. The first flow path 35 is supplied with a first resin containing a foaming agent extruded from the first resin push-out section 3 through an inlet (not shown). An annular first discharge port 33 for discharging the first resin is formed at the most downstream portion of the first flow path 35, that is, at the tip portion of the die 2.

Further, a second flow path 36 having a predetermined gap is formed between the outer peripheral surface of the die 31 and the inner peripheral surface of the die 32. As shown in FIG. 4, a through hole 37 extending in a direction orthogonal to the central axis is formed in the die 32, and through the through hole 37, the second flow path 36 is connected to the second resin extrusion portion 4. The extruded second resin is supplied. An annular second discharge port 34 for discharging the second resin is formed at the most downstream portion of the second flow path 36, that is, at the tip portion of the die 2.

As shown in FIGS. 2 and 3, the die 2 includes a pair of molds 20 a in which the first discharge port 33 and the second discharge port 34 provided at the tip of the die 2 are in contact with the divided surfaces 23 a and 23 b. And 20b, it arrange | positions so that it may be located in the shaping | molding space formed between.

Since the first discharge port 33 provided at the tip of the die 2 is annular, the first resin is discharged from the first discharge port 33 in a tubular shape. The first resin supplied to the first flow path 35 of the die 2 contains a foaming agent (gas). Therefore, when the first resin is discharged from the annular first discharge port 33 at the tip of the die 2, the foaming agent ( Gas) evaporates and the extruded first resin foams. That is, the first resin becomes a tubular foam by being discharged from the first discharge port 33.

Further, since the discharge port 34 of the die 2 provided at the tip of the die 2 is also annular and is provided so as to surround the first discharge port 33, the second resin is a tubular shape made of the foamed first resin. It is discharged in a tubular shape so as to cover the entire outer surface of the foam.

As described above, the interiors of the

molds

20a and 20b are vacuum-sucked through pores (not shown) provided in the recesses of the

molds

20a and 20b or are pressurized by air injection. A tubular foam (first resin foam) coated with resin is pressed against the inner surfaces of the recesses of the

molds

20a and 20b, and a foamed resin tube having the same outer shape as the recesses of the

molds

20a and 20b is molded. Is done. On the outer surface of the molded foamed resin tube 10, the unevenness provided on the inner surfaces of the recesses of the

molds

20a and 20b is transferred to form an embossed pattern. Since the plurality of

molds

20a and 20b are conveyed so as to circulate along the

conveyance paths

21a and 21b, the

molds

20a and 20b in which the foamed resin tube 10 is molded are downstream along the central axis of the die 2. The

molds

20a and 20b that have been conveyed and circulated (in the direction away from the die 2) contact the divided

surfaces

23a and 23b to form a new molding space. Therefore, an embossed pattern is formed on the outer surface by discharging the first resin and the second resin from the first discharge port 33 and the second discharge port 34 at a constant discharge speed while circulating and conveying the plurality of

molds

20a and 20b. The foamed resin tube having a long length can be continuously molded.

FIG. 5 is a perspective view of a part of the foamed resin tube manufactured by the manufacturing apparatus according to the embodiment.

As described above, in the foamed resin tube manufacturing apparatus 1 according to the present embodiment, the first resin containing the foaming agent (gas) is further foamed while being extruded into a tubular shape at the same time inside the

molds

20a and 20b. The surface of the first resin is covered with the second resin, and vacuum molding or air pressure molding is further performed. That is, in the foamed resin tube manufacturing apparatus 1 according to the present embodiment, the foaming of the first resin, the coating of the foam of the first resin with the second resin, and the molding into the tube shape having the embossed pattern on the surface are performed simultaneously. Do. Therefore, the number of manufacturing steps can be greatly reduced as compared with the conventional manufacturing method described in FIG.

Note that the foamed resin tube 10 shown in FIG. 5 is made of a foamed first resin and includes a resin foam 51 having a tubular shape and a film 52 that covers the surface (outer peripheral surface) of the resin foam 51. The embossed pattern on the surface is formed on the film 52 and the outer peripheral surface of the resin foam 51. The foamed resin tube 10 according to the present embodiment is characterized in that it has an integral tube shape with no welding mark (portion corresponding to the joint portion 85 shown in FIG. 6) in a cross section orthogonal to the longitudinal direction. Therefore, the foamed resin tube 10 according to the present embodiment is a foamed resin tube with less cross-sectional shape distortion.

Moreover, in the foamed resin tube manufacturing apparatus 1 according to the present embodiment, since the resin is directly molded into a tubular shape, a stress difference due to the difference in the circumferential length between the inner circumference and the outer circumference of the foamed resin tube 10 does not occur. Therefore, according to the foamed resin tube manufacturing apparatus 1 according to the present embodiment, it is possible to reduce the distortion of the cross-sectional shape and bring it closer to a perfect circle, and thus it is possible to manufacture the foamed resin tube 10 having an excellent aesthetic appearance. In addition, the foamed resin tube formed by the foamed resin tube manufacturing apparatus 1 according to the present embodiment is a product that is excellent in aesthetics in that there is no joint between end faces as shown in FIG.

Furthermore, although the foamed resin tube 10 as in the present invention is used as a heat insulating material for piping, the foamed resin tube 10 may be cut open by making a slit in the longitudinal direction for attachment to the piping. Since the conventional foamed resin tube shown in FIG. 7 is formed by rounding a flat foam into a cylindrical shape, if the slit is made in the longitudinal direction, the opening of the slit portion may be increased. On the other hand, since the foamed resin tube 10 manufactured by the foamed resin tube manufacturing apparatus 1 according to the present embodiment is directly formed in a tubular shape, it can maintain a tubular shape even when a slit is provided in the longitudinal direction. As a result, the workability at the time of attachment to the piping can be improved.

(Other variations)
In the above embodiment, the outer surface of the foam made of the first resin is covered with the second resin film, but the second resin film may be omitted. In this case, a foamed resin tube without a second resin film can be manufactured by using the die described in the above embodiment (see FIG. 4) and not supplying the second resin to the die. Moreover, when manufacturing the foamed resin tube without a 2nd resin film, it has the 1st supply port and the 1st flow path, the die | dye which does not have a 2nd supply port and a 2nd flow path, and 1st resin mentioned above You may comprise a manufacturing apparatus with an extrusion part and a shaping | molding apparatus. Even in the case where the second resin film is not provided, the first resin foaming and the molding into the tube shape having the embossed pattern on the surface are performed simultaneously, thereby making the manufacturing process as compared with the conventional manufacturing method described in FIG. The number can be greatly reduced. In addition, by directly molding the resin into a tubular shape, it is possible to reduce the distortion of the cross-sectional shape and bring it closer to a perfect circle, so that it is possible to manufacture a foamed resin tube with excellent aesthetics.

In the above embodiment, the foamed resin tube having the lattice-like embossed pattern formed on the outer peripheral surface is described as an example. However, as described above, various outer surface shapes can be obtained by changing the concave shape of the mold of the molding apparatus. Can be produced. For example, a corrugated pipe made of a resin foam can be manufactured using a corrugated mold.

The present invention can be used for manufacturing a foamed resin tube used for a heat insulating cover for piping.

DESCRIPTION OF SYMBOLS 1 Foamed resin tube manufacturing apparatus 2 Die 3 1st resin extrusion part 4 2nd resin extrusion part 5 Molding apparatus 10 Foamed resin tube 11 Extruder 12 Extruder 20 Mold 31 Die 32 Die 33 1st discharge port 32 2nd discharge port 35 First channel 36 Second channel 51 Resin foam 52 Film

Claims

An apparatus for producing a foamed resin tube having an embossed pattern on the surface,
A die having an annular first discharge port and a first flow path communicating with the first discharge port;
A first resin supply unit that melts and kneads a thermoplastic first resin, mixes a foaming agent with the melted first resin, and supplies the first resin to the first flow path of the die;
A plurality of first molds having a recess corresponding to a part of the outer surface shape of the foamed resin tube and a plurality of second molds having a recess corresponding to the other part of the outer surface shape of the foamed resin tube are used. A molding apparatus for forming the first resin discharged from the first discharge port of the die into a tubular shape and forming the embossed pattern by performing vacuum molding or pressure molding with air,
The apparatus for producing a foamed resin tube, wherein the first discharge port of the die is disposed in a molding space sandwiched between a recess of the first mold and a recess of the second mold.
The die is further provided with an annular second discharge port and a second flow path communicating with the second discharge port,
A second resin supply unit that melt-kneads the thermoplastic second resin and supplies the molten second resin to the second flow path of the die;
The second discharge port of the die is disposed so as to surround the first discharge port in the molding space sandwiched between the recess of the first mold and the recess of the second mold. The foamed resin tube manufacturing apparatus according to claim 1.
A method for producing a foamed resin tube having an embossed pattern on a surface,
A first mold having a recess corresponding to a part of the outer surface shape of the foamed resin tube and a second mold having a recess corresponding to another part of the outer surface shape of the foamed resin tube are used. An annular first discharge port provided in the die with a molten thermoplastic first resin containing a foaming agent in a molding space sandwiched between the recess of the mold and the recess of the second mold Foamed resin that forms the first resin discharged from the first discharge port of the die into a tubular shape and forms the embossed pattern by performing vacuum forming or pressure forming with air while extruding from the tube Tube manufacturing method.
The die is further provided with an annular second discharge port surrounding the first discharge port,
In the molding space sandwiched between the concave portion of the first mold and the concave portion of the second mold, the molten thermoplastic second material is discharged together with the discharge of the first resin from the first discharge port. The method for producing a foamed resin tube according to claim 3, wherein a resin is extruded from the second discharge port, and the surface of the first resin extruded into the tubular shape is covered with the second resin.
A foamed resin tube having an embossed pattern on the surface and having an integral tube shape with no welding marks in a cross section perpendicular to the longitudinal direction.
The foamed resin tube according to claim 5, comprising a resin foam having a tubular shape and a film covering a surface of the resin foam.