JPH09109280A - Manufacture of foamed resin tube with crest pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a foamed resin tube with a clear-cut and beautiful crest pattern created without the generation of uneven strips such as flash which may be a problem of outward appearance when shaping a crest pattern, and other advantages of excellent surface strength, heat insulating properties and high productivity. SOLUTION: At least, two rolls, each of which has a cylindrical periphery face of a cross section shape consisting of at least, two arcs obtained by splitting a circle and also has a shaping mold 13 located near the cylindrical periphery face, are combined together so that a shaping hole with almost circular cross section face is formed. In addition, a long foam resin tube 6 with a skin layer is continuously supplied into the shaping hole, and then is allowed to run with the concurrent action to press the tube with a rotating roll 11. In this case, a recessed groove 18 is continuously preformed, by an auxiliary roll 16, on the surface of the tube 6 scheduled to pass through the clearance between the joined lateral edges of the adjacent rolls 11, and then this tube 6 with the groove 18 is supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed resin tube having a pattern on its surface, which is preferably used mainly as a covering heat insulating material.

[0002]

2. Description of the Related Art Conventionally, a foamed resin tube made of a highly cross-linked polyethylene foam or the like is generally used as a heat insulating material for covering a refrigerant pipe or the like connected between an outdoor unit and an indoor unit of an air conditioner. Has been done.

On the outer peripheral surface of this type of foamed resin tube,
A film having a skin layer formed by laminating films is used to prevent damage, and the outer surface of the skin layer is usually embossed to give a pattern.

By applying this pattern, it is possible to obtain a strengthening effect of the protective function such that the skin layer is less likely to be torn during handling and the occurrence of external damage during use, and wrinkles are formed during bending. There are many advantages such as occurrence of cracking and buckling are reduced, workability is improved, and a cosmetic effect is imparted to improve appearance quality.

As a method of manufacturing such a foamed resin tube having a pattern, a composite sheet obtained by laminating a film having a pattern on one surface of a foamed resin sheet is curved in the width direction. A common method is to form a tube by the above method, but when a refrigerant pipe or the like is covered with this, there is a problem that surface strength, heat insulating function, etc. are deteriorated because a seam is generated.

In order to solve such a problem, the present applicant has previously extruded a foamed resin tube as described in JP-A-3-207639 (see FIG. 7).
The outer surface thereof is extrusion-coated with a non-foamed resin to form a foamed resin tube p having a skin layer, and then, a plurality of drum-shaped rolls r having a pattern-shaped shaping die d on the body surface are used. The shaping die is arranged so as to form a shaping hole having a substantially circular cross section, and a tube p having a diameter slightly larger than the shaping hole is continuously supplied into the shaping hole. We have developed a technology to manufacture foamed resin tubes with a crest pattern by pressing and shaping.

By the technique described in the above publication, a seamless pattern-patterned foamed resin tube can be manufactured in one step, and a tube excellent in surface strength and a heat insulating function can be manufactured with high productivity.

However, in this shaping apparatus, since the side edges of the rolls r adjacent to each other form a shaping hole,
As shown in FIG. 7, on the surface of the foamed resin tube p, they are lightly contacted with each other or positioned very close to each other, and in any case, the seam of the side edges is generated.

When this seam is pressed and shaped in a state where the seam is generated, the skin layer is caught in the seam or bulges from the seam, so that sometimes a linear "burr" is formed on the surface of the tube p. If "f" occurs and the precision of the seam is not good, the "burr" becomes more unsightly.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems of the prior art, the present invention has excellent surface strength and heat insulating function, and has a problem in appearance such as "burr" when forming a pattern. It is an object of the present invention to provide a method for producing a foamed resin tube having high productivity, which is capable of providing a clear and beautiful pattern without the occurrence of uneven ridges.

[0011]

A method for manufacturing a foamed resin tube with a crest pattern according to the present invention has a body peripheral surface having a sectional shape obtained by dividing a circle into two or more arcs, and shaping the body peripheral surface. Each roll of a shaping apparatus, in which two or more rolls provided with molds are arranged so that each shaping mold forms a shaping hole having a substantially circular cross section, at the same speed. While rotating in the direction
In the method for producing a foamed resin tube with a crest pattern, wherein a long body of a foamed resin tube having a skin layer is continuously supplied into the shaping hole to press and shape the skin layer of the tube, It is characterized in that a continuous groove is formed in advance on the tube surface passing through the joint between the side edges of the rolls adjacent to each other in the shaping apparatus, and the above-mentioned object is achieved thereby.

The roll used in the present invention has two circles.
Use two or more pieces having a body-circumferential surface with a sectional shape divided into two or more arcs. Therefore, for example, when a roll having a sectional shape divided into four arcs is used, it is composed of four roll groups. Further, as will be described later, a shaping die is provided on the circumferential surface of each roll, and the shaping die is provided so as to form a shaping hole having a substantially circular cross section.
To this end, the rolls may be arranged so that the centers of the arcs on the circumferential surface of the rolls coincide with each other.

Further, the shaping pattern of the roll is for pressing a foamed resin tube having a skin layer and embossing a concave pattern, a convex pattern or a concave-convex pattern on its surface to give a pattern pattern. Therefore, the diameter of the shaping hole used is slightly smaller than the outer diameter of the tube. In addition, the pattern referred to here mainly means a pattern in which one or two or more relatively simple-shaped motifs are continuously formed.

The roll has a roll main body and a shaping mold, but the roll may be integrally formed,
Further, the roll main body may be provided with a shaping die made as a separate body. The material cannot be said to be unequivocal depending on the pattern, manufacturing speed, shaping pressure, material of the skin layer of the foamed resin tube, etc. Those made of metal, which is rich in properties, are suitable.

The foamed resin tube having a skin layer used in the present invention is a conventionally known method, that is, the resin tube is extruded and foamed when it leaves the mold, and the foamed resin tube is guided to a coated mold. , And is obtained by coating and extruding another molten resin. In the molding of the foamed resin tube, the foaming means may be a foaming agent decomposition method or a liquid mixing method. The foamed resin tube may or may not be crosslinked. Furthermore, in the case of cross-linking, the method of cross-linking is arbitrary.

Polyethylene, polypropylene and other polyolefin resins are preferably used as the thermoplastic resin used for molding the foamed resin tube, but other materials include urethane resin, vinyl chloride resin, rubber and the like. The thermoplastic resin used for forming the skin layer is also a polyolefin resin such as low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, thermoplastic resin. Examples thereof include elastomers and mixtures of these materials.

The thickness of the skin layer is usually 30 μm to 1 mm.
So, for example, 70-100 in the tube for the air conditioner
μm is preferred.

In order to supply the foamed resin tube having the skin layer to the shaping device, it is preferable to connect the shaping device in series to the next step of the extrusion molding step and the coating extrusion molding step, and to carry out in-line. The foamed resin tube having the skin layer may be molded once and supplied to the shaping apparatus in another step. However, in the case of another step, the tube may need to be reheated.

(Operation) According to the present invention, two or more rolls each having a cylinder peripheral surface having a sectional shape obtained by dividing a circle into two or more arcs and provided with a shaping die on the cylinder peripheral surface, By a shaping device of a shaping device arranged to form a shaping hole having a substantially circular cross section by the shaping die, while rotating each roll in the same direction at substantially the same speed, in the shaping hole, Continuously supplying a long body of a foamed resin tube having a skin layer to press the skin layer of the tube
Since it is shaped, a seamless foamed resin tube having a skin layer can be manufactured with high productivity.

In addition, a continuous groove is formed in advance in the portion of the foamed resin tube supplied to the shaping apparatus that passes through the joint between the side edges of the adjacent rolls forming the shaping holes. Therefore, it is possible to avoid the contact of the surface of the foamed resin tube at the joint, there is no biting of the foamed resin tube, and even if the foamed resin tube swells due to the pressing of the shaping mold, it is absorbed by this concave groove. It

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of an embodiment of the present invention will be described in detail.

FIG. 1 is a schematic view showing an example of a manufacturing apparatus suitable for use in the manufacturing method of the present invention. The manufacturing apparatus is an extrusion molding process for obtaining a foamed resin tube, and a coating extrusion for covering a skin. This is an apparatus in which a shaping device is connected in succession after the process to perform in-line shaping of the pattern on the skin layer.

This manufacturing apparatus has two extruders 1 and 2,
The extruder 1 extrudes a molding material in which a foaming agent is mixed with a thermoplastic resin from a molding die 3 to form a foam, and forms a foamed resin tube 4. Further, the extruder 2 melts and kneads a skin layer forming material made of a thermoplastic resin, guides it to a coating mold 5, coats and laminates it on the outer peripheral surface of the foam resin tube 4, and thus the foam resin tube 6 having a skin layer. To get

FIG. 2A is an enlarged sectional view showing an example of the coating die 5, and FIG. 2B is a schematic sectional view of a foamed resin tube 6 having a skin layer.

The coating die 5 has a resin passage 7 having a circular cross section through which the foamed resin tube 4 is passed, at the center of the extrusion direction thereof.
Further, a covering passage 9 is provided around the outlet of the resin passage 7 into which the skin layer forming material 8 is introduced from one side surface and which is extruded in a cylindrical shape. Therefore, the foamed resin tube 4 fed into the coating mold 5 is coated with the heated skin layer forming material 8 at the place where it exits the coating passage 9, and as shown in FIG.
The foamed resin tube 6 having the skin layer 10 is delivered.

Next, the foamed resin tube 6 having the skin layer thus obtained is fed into the shaping apparatus via the auxiliary roll.

FIG. 3 is an enlarged front view showing the main part of the manufacturing apparatus shown in FIG. 1, FIG. 4 (a) is a perspective view showing only the roll taken out from the same apparatus, and FIG. 4 (b) is the same as above. Of A
FIG. 5 is a cross-sectional view taken along the line A and viewed in the direction of the arrow. FIG. 5C is a plan view in which the shaping mold of the roll is flattened and further enlarged, and FIG. B- in FIG.
FIG. 6 is a cross-sectional view taken along line B and viewed in the direction of the arrow, showing the foamed resin tube 6 omitted, and FIG. 6B shows the foamed resin tube 6 immediately before being supplied to the shaping apparatus. FIG.

In these figures, 11 is a roll, and in the case of this example, it is composed of a group of 4 rolls.
The shape forming hole 12 having a substantially circular cross section is formed by arranging as shown in FIG. The outer diameter of each part is 200 mm, the shaping hole is 24 mm, and the material is SUS304.

Further, the roll 11 has a drive source (not shown) at substantially the same speed and in the same direction so that the foamed resin tube 6 having the skin layer can be pinched in the manufacturing direction (left to right in the drawing) in FIG. There is provided a drive mechanism that is rotated by the power from. Therefore, in the case of this example, each roll 1
Although No. 1 uses a speed tuning device (not shown) using a computer, the speed may be manually adjusted instead.

Denoted at 13 is a shaping die provided on the circumferential surface of the body. As shown in FIG. 4C, the bottom side = 2 mm × 2 mm,
An inverted quadrangular pyramid-shaped recess 14 having a depth of 1 mm is engraved in order, and the foamed resin tube 6 having the skin layer 10 is formed.
By pressing on, the surface layer 10 is provided with a crest pattern in which quadrangular pyramid-shaped convex portions are juxtaposed in parallel. The roll body and the shaping die 3 are integrally formed, and are entirely made of stainless steel. Thus, the shaping device 15 is configured.

By the way, at the positions where the shaping holes 12 of the rolls 11 are formed, the side edges of the rolls 11 adjacent to each other are slightly contacted with each other or a very slight gap is opened. They are arranged (this example shows an example in which a gap is provided). Due to the joints between the respective side edges, for the reasons described above, continuous streak-like "burrs" can be formed on the outer peripheral surface of the tube 6 corresponding to the joints in parallel with the axis thereof.

In the present invention, in order to prevent the occurrence of this "burr", a groove is formed on the outer peripheral surface of the tube 6 which is to pass through the seam and is continuous in the traveling direction of the tube 6. Put it down. The means is not particularly limited, but the simplest and most effective means is shown in FIGS.
Shown in

In these drawings, reference numeral 16 denotes auxiliary rolls, which are arranged at four intervals in the circumferential direction of the tube 6. The arrangement position is, in the circumferential direction of the tube 6,
As shown in FIG. 5A, it is a portion that passes through the seam, and the peripheral edge of the auxiliary roll 16 causes the tube 6
In order to be able to press, the peripheral edge is at a position slightly depressed from the mold surface of the shaping mold 13 toward the center of the arc.

Further, in the manufacturing direction, as shown in FIG. 3, it is a distance L from the position where the surface of the tube 6 contacts the roll 11 to the front side. Normally L = 20-30m
m. It should be noted that the size of the above-mentioned drop is preferably 1 mm or less. Therefore, it is preferable that the depression size can be freely adjusted.

The material of the auxiliary roll 16 of this example is SUS30.
4, a bearing 17 is fitted to a bearing shaft (not shown) so as to be in contact with the surface of the tube 6 and rotate by the friction. The dimensions of each part are: outer diameter = 30 mm,
Thickness = 2 mm, and its peripheral portion is formed so that its cross section becomes an equilateral triangle, and its edge is edged to R = 2 mm.

The foamed resin tube 6 having the skin thus shaped becomes a foamed resin tube P with a pattern and is wound up by the winder 19. In addition, 20 and 20 are guide rolls.

(Example 1)

Using the above manufacturing apparatus, first, the extruder 1
Then melt and knead low-density polyethylene with a melt index of 2.0 and a density of 0.92 in the first half of the barrel, and press the dichlorodifluoromethane foaming agent under pressure from the center of the barrel to thoroughly knead it, and then from the molding die 3 into a tube. Extruded into a shape. The molten resin was discharged from the tip of the molding die 3 and simultaneously foamed to obtain a foamed resin tube 4 having an inner diameter of 7 mm and an outer diameter of 25 mm.

Subsequently, a linear low-density polyethylene having a melt index of 5.0 and a density of 0.935 is extruded from the extruder 2, and the covering die 5 is used to cover the entire outer peripheral surface of the foamed resin tube 4 with a thickness of 100 μm. Coated with non-foamed resin
By laminating, a foamed resin tube 6 having a skin layer 10 was obtained.

Next, it is fed to the auxiliary roll 16 and the concave groove 1
8 was formed and guided to a shaping device 15 to form a pattern on the entire outer peripheral surface thereof. The auxiliary roll 16 was arranged at a position where its peripheral edge had dropped 0.3 mm from the surface of the shaping mold 13 and L in FIG. 3 was 30 mm.

Thus, the foamed resin tube P with the pattern is formed.
Was obtained and was wound by the winder 19. The manufacturing speed at that time was 13 m / min. There is no "burr" at the seams of the rolls, only a thin line remains,
In addition, the obtained tube P had a clear pattern and a quadrangular pyramid height of about 1 mm was secured, and it was a beautiful tube with no problem in size or the like.

(Example 2)

A tube P was obtained in the same manner as in Example 1 except that the resin used for forming the skin layer was low density polyethylene having a melt index of 18 and a density of 0.920. The appearance of the joint was similar to that of Example 1, and the obtained tube P had a clear pattern and a quadrangular pyramid height of about 1 mm.

(Embodiment 3)

A tube P was obtained in the same manner as in Example 1 except that the fall of the auxiliary roll was changed from 0.3 mm to 0.6 mm. The appearance of the seam is width = 0.5m
The line of m and depth = 0.3 mm remains, which is not a problem in appearance, and the obtained tube P has a clear pattern and a pyramid height of about 1 mm is secured. There was no problem.

(Comparative example)

Except that no auxiliary roll was used,
A tube P was obtained in the same manner as in Example 1. In the obtained tube P, the pattern was clear and the height of the quadrangular pyramid was secured to be about 1 mm, but a “burr” of height = 2 to 4 mm was generated at the joint of the rolls, and the shaping speed was increased. I made various changes,
There was no change in the size of the "flash" and the appearance quality was poor.

[0048]

According to the manufacturing method of the present invention, the shaping hole of the shaping apparatus having the shaping hole formed by two or more rolls having the shaping pattern of the pattern on the circumferential surface of the body is provided. Inside, a long body of a foamed resin tube having a skin layer is continuously supplied to press and shape the tube to produce a seamless pattern-patterned foamed resin tube. Since a continuous groove is formed in advance in the part of the forming device that passes through the joint between the side edges of adjacent rolls, "burrs" are prevented from occurring, and surface strength and heat insulation are prevented. Not only the function but also the appearance quality can be manufactured with high productivity.

Therefore, the foamed resin tube having the skin layer obtained by the production method of the present invention has a clear and beautiful pattern on the surface thereof, and is suitable for use as a covering heat insulating material for air conditioners and other applications. It is something.

[0050]

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a manufacturing apparatus suitable for use in the manufacturing method of the present invention.

FIG. 2A is an enlarged cross-sectional view showing an example of a coating die, and FIG. 2B is a schematic cross-sectional view of a foamed resin tube having a skin layer.

FIG. 3 is an enlarged front view showing a main part of the device of the present invention shown in FIG.

FIG. 4 (a) is a perspective view showing only a roll taken out from the same device, and FIG. 4 (b) is a sectional view taken along line AA of the same and seen in the direction of the arrow. FIG. 3C is a plan view showing the shaping mold of the roll in a flat shape and further enlarged.

5 (A) is a cross-sectional view taken along line BB in FIG. 3 and viewed in the direction of the arrow, in which a foamed resin tube having a skin layer is omitted. (B) is a cross-sectional view of a foamed resin tube having a skin layer immediately before being supplied to a shaping device.

FIG. 6 is an enlarged cross-sectional view showing an example of an auxiliary roll.

FIG. 7 is a perspective view showing an example of a manufacturing apparatus used in a conventional manufacturing method.

[Explanation of symbols]

 p Foamed resin tube having a skin layer d Shaped mold r Drum roll f Burr P Foamed resin tube with crest pattern 1 Extruder 2 Extruder 3 Molding die 4 Foamed resin tube 5 Covering die 6 Foamed resin having a skin layer Tube 7 Resin path with circular cross section 8 Skin layer forming material 9 Covering path 10 Skin layer 11 Roll 12 Shaping hole 13 Shaping mold 14 Reverse quadrangular pyramid recess 15 Shaping device 16 Auxiliary roll 17 Bearing 18 Groove 19 Winding Machine 20 guide roll

Claims (1)

[Claims] 1. Two or more rolls each having a cylinder peripheral surface of a sectional shape in which a circle is divided into two or more arcs and provided with a molding die on the cylinder peripheral surface, each of which has a molding die. Foaming having a skin layer in the shaping hole of a shaping device arranged to form a shaping hole having a substantially circular cross section while rotating each roll in the same direction at substantially the same speed. In a method for producing a foamed resin tube with a crest pattern, which is configured to continuously supply a long body of a resin tube to press and shape the skin layer of the tube,
A method for producing a foamed resin tube with a crest pattern, wherein a continuous groove is formed in advance on the tube surface passing through the joint between the side edges of the rolls adjacent to each other in the shaping apparatus, and is supplied.