JPH0667585B2 - Ultra-high molecular weight polyolefin-coated metal wire and manufacturing equipment for metal wire - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ultrahigh molecular weight polyolefin-coated metal wire and a coated metal wire manufacturing apparatus.

[Conventional technology]

Ultra-high molecular weight polyolefin represented by ultra-high molecular weight polyethylene is superior to general-purpose polyethylene in impact resistance, abrasion resistance, chemical resistance, tensile strength and the like, and its application is expanding as an engineering plastic. However, it has extremely high melt viscosity and poor fluidity compared to general-purpose polyethylene, so it is very difficult to mold by extrusion molding or injection molding, and most of them are molded by compression molding. At present, rods and the like are extruded at an extremely low speed.

On the other hand, widely used polyethylene is widely used as an anticorrosive coating material for wires and a coating material for electric wires and cables.As a coating method, polyethylene melted by an extruder is supplied to a crosshead die, The method of covering an electric wire or the like is adopted. However, as mentioned above, ultra-high-molecular-weight polyethylene has a much higher melt viscosity than general-purpose polyethylene, so apart from melting in an extruder, the resin pressure (back pressure) in the crosshead rises sharply and extrusion molding is difficult. Also, even if extruded, the molten resin separated at the crosshead cannot be fused at all in a short die, and it is impossible to obtain an ultrahigh molecular weight polyolefin-coated metal wire having good appearance and performance. It was.

[Problems to be solved by the invention]

In view of such a situation, the present inventors have conducted various studies to develop a method for coating an electric wire or the like with ultrahigh molecular weight polyolefin, and as a result, connected a tube die having an L / D of 5 or more to the tip of the extruder, and The mandrel is directly connected to the screw tip of the extruder.The mandrel is screwed from the rear of the molding machine, and the core wire is passed through the mandrel. It was found that an ultra-high molecular weight polyolefin-coated metal wire having excellent wear resistance and having no self-lubricating property was obtained, and the present invention was completed.

[Means for solving problems]

That is, the present invention is characterized in that an ultrahigh molecular weight polyolefin having an intrinsic viscosity [η] of 5 to 25 dl / g is coated on the periphery of a metal wire, the coating has a uniform thickness, no weld defects, and self-lubricating property. There is an excellent abrasion resistance, ultra-high molecular weight polyolefin-coated metal wire rod and extruder side, an extruder consisting of a grooved cylinder and a screw with a compression ratio in the range of 1 to 2.5, and a screw connected to the tip of the screw At least L / D composed of the mandrel and the outer die rotating with rotation is 5, and the ratio (S ₁ / S ₂₎ of the resin flow passage cross-sectional area S ₁ at the tube die inlet and the resin flow passage cross-sectional area S ₂ at the middle of the tube die. ) is in the range of the ratio (S ₂ / S ₃₎ to 1.0 to 3.0 of the cross-sectional area S ₃ of the resin flow path sectional area S ₂ and Chiyubudai resin flow path at the outlet of the scope and Chiyubudai middle portion of 0.5 to 3.0 healing Device for producing a thermoplastic resin-coated metal wire rod, which comprises a core portion for feeding the core wire and a conduit for feeding a core wire extending from the outside of the resin supply port of the die and the screw to the outside of the tip of the mandrel Is provided.

[Work]

The ultrahigh molecular weight polyolefin used in the present invention has an intrinsic viscosity [η] measured at 135 ° C. in a decal solvent of 5 to 25 dl.
/ G, preferably 8 to 25 dl / g, homopolymer of α-olefin such as ethylene, propylene, 1-butene, 4-methyl-1-pentene or α-olefin and other α.
-A copolymer with olefin or a copolymer of α-olefin with a vinyl compound such as vinyl acetate, vinyl chloride, acrylic acid and acrylic ester, which is crystalline. Among these ultrahigh molecular weight polyolefins, homopolymers of ethylene or ethylene and other α-olefins,
For example, a so-called ultra-high molecular weight polyethylene, which is a crystalline copolymer of ethylene with propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, etc. , Excellent in cold resistance, weather resistance, abrasion resistance, self-lubricating property, mechanical strength, chemical resistance, etc., and has a moderately high melt viscosity, so that the mandrel holding property is good and the melted resin and mandrel This is preferable because a coated metal wire having a uniform thickness can be obtained without twisting or bending of the mandrel due to co-rotation.

Those having an intrinsic viscosity [η] of less than 5 dl / g are preferable because the obtained coating material has low mechanical strength and the melt viscosity is low, so that the effect of correcting the twist and bending of the mandrel by the molten resin during molding tends to be poor. Absent.

The ultrahigh molecular weight polyolefin-coated metal wire of the present invention has the above-mentioned intrinsic viscosity [η] uniformly coated on the metal wire and its periphery.
Of 5 to 25 dl / g of ultra-high molecular weight polyolefin coating. The metal wire may be a single wire or a stranded wire composed of a plurality of wires. Also, metal wire rods are copper, iron,
It is made of zinc, aluminum, or alloys thereof such as stainless steel.

The periphery of the metal wire may be directly coated with ultra-high molecular weight polyolefin, or an adhesive such as an epoxy resin adhesive, a polyisocyanate adhesive, a polyester adhesive, an acrylic resin adhesive may be used to improve adhesion. It may be coated via a nitrile rubber adhesive, an unsaturated carboxylic acid or its derivative graft-modified polyolefin adhesive, or the like. Among these adhesives, unsaturated carboxylic acid or a derivative thereof graft-modified polyolefin adhesive is particularly preferable because it has a relatively low melting point and melts at a temperature near the melting point of the ultrahigh molecular weight polyolefin and facilitates adhesion.

The ultrahigh molecular weight polyolefin-coated metal wire of the present invention usually has a diameter of the metal wire of 0.1 to 30 mmφ, preferably 0.5 to 10 mmφ,
The coating material usually has a thickness of 0.05 to 10 mm, preferably 0.1 to 5 mm.

This technique can also be applied to steel pipe coating.

The apparatus for producing a thermoplastic resin-coated metal wire according to the present invention comprises, as shown in FIG. 1, an extruder 1 side, a grooved cylinder 2 and a screen 3 having a compression ratio of usually 1 to 2.5, preferably 1.3 to 1.8. At least L / D of the extruder 1, the mandrel 5 connected to the screw tip 4 and rotating with the rotation of the screw, and the outer die 6 is at least 5, preferably 10, more preferably 30 to 70, and the resin of the tube die inlet portion 71. The ratio (S ₁ / S ₂ ) of the cross-sectional area S ₁ of the flow path to the cross-sectional area S ₂ of the resin flow path of the tube die intermediate portion 72 is 0.5 to 3.0, preferably 1.0 to 2.0, and the ratio of S ₂ to the tube die outlet 73 is the ratio of the cross-sectional area S ₃ of the resin flow path (S ₂ / S ₃₎ is
It comprises a tube die in the range of 1.0 to 3.0, preferably 1.1 to 2.0, and a core wire feeding conduit 8 extending from the outside of the resin supply port side of the screw to the outside of the tip of the mandrel and the center of the screw and the core of the mandrel. It

The groove portion 21 of the grooved cylinder 2 stably supplies a thermoplastic resin such as ultra high molecular weight polyethylene powder to the compression portion 22. Further, if the compression ratio of the screen 3 is less than 1.0, the compression stress of the resin against the wall surface of the cylinder is small and the extrusion amount becomes unstable, so that the appearance of the product due to the surging phenomenon or poor degassing is likely to occur. On the other hand, when it exceeds 2.5, the resin temperature abnormally rises due to the clogging phenomenon and frictional heat in the compression part 22, and the molecular weight bottom of the resin becomes remarkable due to thermal decomposition, and the friction coefficient and abrasion resistance of the physical properties of the product are impaired. Is generated, which is not preferable.

In FIG. 1, the mandrel 5 is screwed to the tip of the screw 3. Other methods include fixing, fitting or inserting, and mounting with a joint or the like intervening. However, the method of directly screwing the mandrel onto the screw tip as shown in Fig. 1 is simple and can be removed. There are advantages such as easy disassembly and cleaning of the machine die and change of the inner diameter size.

When the L / D of the tube die is less than 5, the molten resin is not completely fused and a thermoplastic resin-coated metal wire having a good appearance cannot be obtained.

The L / D of the tube die is the ratio of the length from the tube die inlet 71 to the tube die outlet 73 and the inner diameter of the outer die 6 at the tube die outlet 73. There is no particular problem if S ₁ / S ₂ is in the range of 0.5 to 3.0, but if the S ₂ / S ₃ ratio is less than 1.0, the molten resin will not be completely fused, while if it exceeds 3.0, the resin pressure will be excessive. Therefore, extrusion molding of the covering material becomes difficult.

As described above, the flow channel area of the tube die basically becomes narrower toward the outlet of the tube die. That is, it is a taper die.

A wire drum is usually provided outside the screen resin supply port.
A core wire delivery device including, for example, a delivery roll 13 and the like is provided for continuously supplying the core wire 12 wound around 11 or the like to a core wire delivery conduit of an extruder. Further, the core wire may be previously coated with the above-mentioned adhesive, or an extruder is separately installed before or after the core wire feeding device, and the core wire is made of modified polyolefin or the like melted in the extruder by passing the core wire through the coating crosshead die. It may be extrusion coated in advance and supplied to the core wire delivery conduit of the extruder. When the core wire is introduced into the core wire delivery conduit of the extruder and treated with a solvent such as acetone or preheated by an electric heater, the effect of fusion with the core wire is further enhanced.

Although a take-up device (not shown) is provided on the downstream side of the tube die outlet 73, a sizing die 14, a cooling water tank 15, and a take-up roll 16 are provided between the tube die outlet and the take-up device.
Etc. may be installed, or an annealing cylinder may be installed instead of the cooling water tank.

In order to produce the ultra-high molecular weight polyolefin-coated metal wire of the present invention using the coated metal wire producing apparatus of the present invention, the ultra-high molecular weight polyolefin is placed in an extruder at a temperature higher than its melting point and lower than its decomposition temperature. Melt and knead with
After transferring to the tube die, the metal wire rod fed from the core wire feeding conduit at the center of the mandrel at the outlet of the tube die may be extrusion-coated and then cooled.

〔The invention's effect〕

The ultra-high molecular weight polyolefin-coated metal wire of the present invention has a uniform coating thickness and does not cause welds, and has a mechanical strength such as tensile strength, impact resistance, and abrasion resistance, which are features of ultra-high molecular weight polyolefin. The metal wire coated with ultra-high molecular weight polyethylene is especially excellent in cold resistance,
It has excellent weather resistance, self-lubricating property, electrical insulation, etc.
By utilizing such characteristics, it can be suitably used for control cable inners, electric wires, and the like.

Further, by using the thermoplastic resin-coated metal wire manufacturing apparatus of the present invention, since the melt viscosity is extremely high, when a conventional cross-head die for extrusion coating is used, the back pressure is too high and extrusion molding is difficult. Moreover, even if it is extruded, a weld defect occurs in the coating material, and it is difficult to obtain an extruded coating wire by a conventional apparatus, and thus a coated metal wire of ultrahigh molecular weight polyolefin can be easily manufactured. Further, the manufacturing apparatus of the present invention is not limited to the conventional thermoplastic resin in the apparatus equipped with a conventional crosshead die or the like, but is not limited to the ultra-high molecular weight polyolefin, as long as its melt viscosity becomes extremely low. , General purpose polyolefin, polyamide,
It has the versatility that other thermoplastic resins such as polyester, polycarbonate and polyvinyl chloride can also be used.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

Example 1 An ultrahigh molecular weight polyethylene-coated metal wire rod was manufactured by using the coated metal wire rod manufacturing apparatus shown in FIG.

Screen outer diameter 30mmφ, screen effective length (L / D)
34, flight pitch 20mm constant, screen compression ratio 1.8,
Adapter length 200 mm, tube die 550 mm, tube die length (L / D) 25, die outlet outer die inner diameter 22 mm
φ, die exit mandrel outer diameter 18mmφ, S ₁ / S ₂ = 1.40, S ₂
/ S ₃ = 1.57, equipped with a 6mmφ core wire delivery conduit extending inside the screw and inside the tube die mandrel, sizing die, cooling water tank, take-up roll and product winder. Ultra high molecular weight polyethylene [η]: 16dl / g, MFR:
Less than 0.01g / 10min, melting point: 136 ℃ and bulk density: 0.45g / cm ³
Extruder, adapter (A) using the powdered resin (trade name: Heizex Million 240M, manufactured by Mitsui Petrochemical Industry Co., Ltd.)
D), the die base (D ₁ ) and the die end (D ₂ ) are set to 280 ℃, 270 ℃, 180 ℃ and 150 ℃ respectively, and the screw rotation speed is set to 15rpm. While pulling at a speed of / min, a copper wire with a diameter of 1.2 mm was fed from a 6 mmφ core wire feeding conduit extending inside the screw and the mandrel of the tube die to coat the ultra high molecular weight polyethylene extruded from the tube die. , Coating pressure
A coated copper wire rod having an outer diameter of 0.3 mm and an outer diameter of 1.8 mm was manufactured. The coating thickness of the obtained ultra high molecular weight polyethylene was uniform both in the periphery and in the length direction.

Example 2 19 strands and a stranded wire having an outer diameter of 1.5 mm were coated with ultra-high molecular weight polyethylene under the same apparatus and conditions as in Example 1. The obtained coated wire rod has a film thickness of 0.25 mm and an outer diameter of 2.
It was 0 mm. The film thickness was uniform both in the periphery and in the length direction.

Example 3 The same apparatus as in Example 1, under the same molding conditions, a 1.0 mm copper wire was preliminarily grafted with maleic anhydride in an amount of 0.15% by weight and MFR of 3.5.
g / 10min maleic anhydride graft modified polyethylene
A 100 μ thick coated core wire was coated with ultra-high molecular weight polyethylene in the same manner as in Example 1 to obtain a coated wire having an outer diameter of 1.5 mm. The film thickness of the obtained coated wire was uniform both in the circumference and in the length direction, and the adhesion between the wire and the coating was excellent.

[Brief description of drawings]

FIG. 1 shows a front sectional view of a coated metal wire manufacturing apparatus according to the present invention. 1 ... Extruder, 5 ... Mandrel 6 ... Outer die, 12 ... Core wire

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B29L 31:34 4F

Claims (2)

[Claims] 1. An ultra-high molecular weight polyolefin-coated metal wire, comprising an ultra-high molecular weight polyolefin having an intrinsic viscosity [η] of 5 to 25 dl / g, which is coated around the metal wire. 2. From the extruder side, at least an extruder comprising a grooved cylinder and a screw having a compression ratio in the range of 1 to 2.5, a mandrel and an outer die which rotate with the rotation of the screw connected to the tip of the screw. L / D is 5, the ratio (S ₁ / S ₂ ) between the resin flow passage cross-sectional area S ₁ at the tube die inlet and the resin flow passage cross-sectional area S ₂ at the middle of the tube die is in the range of 0.5 to 3.0, and the tube die the ratio of the resin flow path sectional area S ₂ and the resin flow path cross-sectional area S ₃ of the tube die outlet of the intermediate portion (S ₂ / S ₃₎ is 1.0 to tube die and the screw of the resin supply port side outside the range of 3.0 To the outside of the tip of the mandrel, a thermoplastic resin-coated metal wire manufacturing apparatus comprising: a screw central part and a core wire feeding conduit extending in the central part of the mandrel.