JPS61199921A - Cooling of melt-extrusion molded product and device thereof - Google Patents

Abstract

PURPOSE:To improve the uniformly of cooling and cooling effect and consequently enhance the productivity by a method wherein cooling water solution is led upwards against the running of thermoplastic resin molded product in a cooling tube in order to cool the molded product. CONSTITUTION:A spacer 6 led out of a rotating die 2 is inserted in a cooling tube 7, past through a centering guide 16, wound to a lower pulley 4, brought into contact with cooling water 14 in a water tank 12 and led outside. Because the spacer 6 is fed in the cooling tube 7 with uniform liquid level, no delay is the cooling starting points in the cross-sectional direction of the spacer occur, resulting in being uniformly cooled cross-sectionally. Consequently, a molded product, at the rib portion of which no strain develops and the groove width of which is uniform, is obtained. Surfactant added in the cooling water 14 makes difficult in generating ruggedness in spiral groove, which is caused by the air in the water and by the bubbles made through the boiling of the water contacting with the surface of the spacer 6.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermoplastic resin molded product having a complex cross-sectional shape;
The present invention relates to a cooling 2J1 method and a cooling fA apparatus for so-called irregular cross-section extruded products, and particularly to a cooling method and apparatus suitable for irregularly shaped extruded products such as those in which spiral grooves are formed in the longitudinal direction of a crystalline thermoplastic resin.

(Prior Art and its Problems) In general, a thermoplastic resin profile extrusion molded product is extruded from a gouer and then subjected to a cooling process using various cold processes.

This cold 2J1 method uses the raw material resin used for extrusion molding,
The method is selected depending on the shape of the molded product. For example, for non-grade resins such as polystyrene, polymethyl methacrylate, hard vinyl chloride, and Arede 1-cellulose, there is a method using air as a refrigerant, and a method using polyethylene, nylon, and polypropylene is used. It is said that for crystalline resins such as these and molded objects with symmetrical shapes, it is better to cool them with water.

On the other hand, a spiral spacer used as an element of an optical fiber cable is similar to the above-mentioned profile extrusion molded product of thermoplastic resin. This spiral subey usually has a structure in which a tensile strength line is placed in the center of its cross section, and a plurality of spiral grooves extending in the longitudinal direction are formed on the outer periphery of the tensile strength line using thermoplastic resin. as,
Polyethylene resins such as high-density polyethylene are mainly used from the viewpoint of physical properties such as mechanical strength and weather resistance, and raw material costs.

Therefore, it is desirable to use water as a cooling medium in the molding of the spiral spacer of this scale from the viewpoint of cooling effect and economy, but in conventional profile extrusion, generally horizontal extrusion from the die and water are used. In cooling using a refrigerant, there are problems mainly in the method of sealing water at the entrance and exit of the cooling tank, and problems such as uneven cooling due to slow contact with water make it impossible to obtain a desired cross-sectional shape.

Considering the symmetry of sealing and cooling of this water, we tried a method of extruding it vertically from a die and directly guiding it to a water tank filled with cooling water for cooling, but the grooves were shaped like avatars due to the number of bubbles in the spiral grooves. There were problems such as.

In addition, when using this method, it is necessary to change the orientation of the molded product in the water tank in relation to the withdrawal, and cooling assimilation must be almost completed by the time this direction is changed.
For this reason, a considerable depth of water is required and the water tank is quite large, making it difficult to insert the water into the tank, adjusting the air gear 11 between the extrusion die and the water surface, balancing cold W and production speed, and manufacturing costs for the equipment. There was a problem with that.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to cool a profile extruded product such as a helical spacer used as an element of an optical fiber cable. An object of the present invention is to provide a cooling method and apparatus that can provide good cooling uniformity and effectiveness in cooling, thereby improving productivity.

(Means for Solving the Problems) In order to achieve the above-mentioned object 1, the present invention provides a thermoplastic resin molded product that is melt-extruded vertically downward, and when cold-IJIed, the thermoplastic resin molded product is The gist of the method invention is that a cooling aqueous solution containing an activator is cooled by being guided into a cooling cylinder in which the thermoplastic resin molding has an upward flow from below against the running of the thermoplastic resin molded product, In a device that cools a thermoplastic resin molded product extruded downward,
A vertically movable cooler 1 is provided directly below the die.
41 cylinder and a water tank provided below the cooling cylinder,
The molded product is inserted into the cooling tube and introduced into the water tank, and cooling water in which a surfactant is dissolved is circulated and supplied to the 11 cooling tubes in a direction opposite to the running direction of the molded product. This is the gist of the invention.

To explain in more detail, the surfactant used in the cooling aqueous solution is preferably one that has good wettability to the extruded product of thermoplastic resin and generates few bubbles.From this point of view, anionic surfactants, Nonionic surfactants are preferable, and combinations thereof or antifoaming agents may also be used.

In addition, the flow rate, flow ω, etc. of the cold W aqueous solution from the bottom to the top in the cooling cylinder are determined by the extrusion molding speed or the extrusion amount, but when the flow rate is VW, the ratio to the running speed VO of the molded product is VW / It is desirable that the VO is approximately in the range of 0.5 to 0.8, and it is desirable that the upward flow in the cooling cylinder be in a laminar flow state.

Furthermore, the surfactant concentration in the cooling aqueous solution should be about 5% or less, and the liquid temperature should be 40° C. or less, more preferably 20° C. or less, from the viewpoint of cooling effect, so the use of a freezing device is recommended.

(Function of the Invention) As described above, the present invention guides the thermoplastic resin molded product extruded vertically downward from the die into the cooling cylinder with a uniform liquid level.
Since there is no slow cooling start point in the cross-sectional direction of the molded product, the cross-sectional direction is uniformly cooled, and, for example, a spiral spacer with no slope of the rib portion and a uniform groove width can be obtained.

In addition, since a surfactant is added to the cooling water solution, in conventional cooling using only water, air bubbles attached to the surface of the molded product may be generated due to air in the water or boiling of water that comes into contact with the surface of the molded product. ! ll! Irregularities in the spiral groove portion are prevented by the surfactant's effect of promoting foam layer formation.

Furthermore, since the cooling cylinder circulates the cooling aqueous solution in an upward flow from the bottom to the top, it is difficult to form a temperature boundary layer near the molded product, so the cooling performance can be improved.
In addition, since a cooling cylinder having an outer diameter of at most 1Qcm is sufficient, the air gap between the die discharge surface and the cooling liquid level can be adjusted by using only the cooling cylinder, which simplifies the equipment.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The figure shows an embodiment of a cold 2J1vt installation according to the present invention.

The cooling device shown in the figure includes a rotary die 2 supported by a gate-shaped frame 1 so that the discharge port faces vertically, and a rotary die 2 that is rotatable so that the vertical axis of the rotary die 2 and the tangent to the outer circumference coincide with each other. A shaft-supported upper and lower pulley 3.4 are arranged, and the upper pulley 3.
The tensile strength wire 5 supplied through the rotary die 2 is erased by the molten thermoplastic resin supplied through the extrusion molding machine, and a spiral groove of a predetermined pitch is formed on the outer periphery of the optical fiber carrier. This is a cooling device for a space Fj6, and is configured as follows.

1. Directly below the rotary die 2, a cylindrical cold IA cylinder 7 having the same vertical axis is installed, and at the lower end of the cold fJJ cylinder 7 there is a seal with the same cross-sectional shape as the spacer 6. A plate 8 is attached.

Further, the cooling cylinder 7 is supported by an upright support 9 via a grip piece 10, and the grip piece 10 is screwed onto the support 9, and by rotating a handle 11, the cooling WGW 8 can be moved up and down. Moving.

A water tank 12 is provided below the cooling cylinder 7, and a portion of the lower pulley 4 enters into the water tank 12.

The water tank 12 stores cold W water 14 (a surfactant is added to this cooling water 14) that has been heat exchanged in the refrigeration device 13, and the cooling water 14 in the water tank 12 is pumped. 1
rF17 is supplied to the lower end of the cooling cylinder 7 through rF17
After flowing in a layered manner from the bottom to the top, the cooling water 14 overflows from the upper end of the tube 7 and is returned to the refrigeration device 13, whereupon the cooling water 14 is circulated as shown by the arrows in the figure.

The spacer 6 led out from the rotary die 2 is inserted into the cooling cylinder 7 through the air gap between the tip of the die 2 and the cooling cylinder 7, passed through the centering guide 16, and wound around the lower pulley 4. After coming into contact with the cooling water 14 in the water tank 12, it is led out to the outside.

The inside of the cooling cylinder 7 is filled with cooling water 14, and the spacer 6
This flows in the opposite direction to the direction of travel.

When the spacer 6 is cooled with the cooling device configured as described above, the spacer 6 extruded vertically downward from the rotary die 2 is introduced into the cold NJ tank 7 with a uniform liquid level, so that the spacer 6 is cooled in the cross-sectional direction. There is no delay in the starting point, the cross-sectional direction is uniformly cooled, there is no distortion of the rib portion of the spacer 6, and a uniform iM width can be obtained.

In addition, since a surfactant is added to the cooling water 14, unlike a conventional water-only cooling axle, the air in the water and the air bubbles that come into contact with the surface of the spacer 6 boil and form a spiral. It becomes difficult for unevenness to occur in the groove portion.

This is based on the foaming and promoting action of the surfactant.

Furthermore, the cooling water 14 in the cold double cylinder 7 is an upward flow from below to the top, and since the cold double water 14 is circulated, a temperature boundary layer is not generated near the spacer 6, and the spacer 6 is Can be cooled sufficiently.

Furthermore, by vertically moving the cooling cylinder 7, the air gap between the die 2 and the cooling liquid level can be easily adjusted.

The present inventors confirmed the effects of the above-mentioned apparatus and cooling method using the following specific examples and comparative examples.

(Example 1) A twisted steel wire with an apparent outer diameter of 1.8 mm, which was made by twisting steel wires with an outer diameter of 0.6 mm into a (1+6) structure, was used as the tensile strength wire 5, and the rotating die 2 was attached to it. Insert the cross into the RAD die and apply high-density polyethylene of M[=0.15 to the die part
The uncooled III-shaped molded product was coated by extrusion at 10° C. from a rotary die 2 corresponding to the cross section described below, and was coated with anionic interfacial viscosity agent Rho 1-oil (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., 2 active ingredients: 60%).
) in a freezing device 13 at 10°C.
Cooling water 14, which has been cooled to 11, is pumped through a pump 15 into a cold 14' cylinder 7 with an inner diameter of 6.8 cm and a diameter of 80 cm.
It was supplied at a flow rate of f/hr, overflowed from the upper end thereof, and cooled by inserting the spacer 6 into the cooling cylinder 7 at a speed of 3.5 m/min.

This thing has five spirals on the outer periphery of the tensile strength line 5, and the target diameter of the rib part is 9 mm, the valley diameter of the groove part is 4.2III11, and the pitch of the spiral is 400 mm.
711, a good shape with no inclination of the rib portion and no unevenness on the surface was obtained.

Note that the upward flow velocity of the cooling water 14 in the cooling cylinder 7 in this example was 2.3 m/min.

(Example 2) In producing a spiral spacer 6 having the same configuration and shape as in Example 1, a nonionic ester surfactant (manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) prepared by esterifying lauric acid and polyethylene glycol was used as the cooling water 14. :Product name Briand L-400
) was used, extrusion molded in the same manner as in Example 1, and cooled.

The spiral spacer 6 thus obtained also had a good shape as in Example 1.

(Comparative Example 1) A spacer 6 was produced in the same manner using tap water instead of using a surfactant as the cold 7JI water 14.

As a result, many irregularities were generated in the spiral groove of the spacer.

(Effects of the Invention) As described above in detail in the Examples, according to the method and apparatus of the present invention, it is possible to uniformly cool a melt-extruded product, maintain a good shape of the molded product, and The surfactant attached to the surface of the molded product provides an antistatic effect and smoothness to the surface of the molded product, improving its suitability for use. Excellent effects can be obtained by being able to adjust the inside of the cylinder.

[Brief explanation of drawings]

The figure is a side view showing one embodiment of the present invention.

Claims (2)

[Claims] (1) In a method of cooling a thermoplastic resin molded product that has been melt-extruded vertically downward, a cooling aqueous solution containing a surfactant is applied to the thermoplastic resin molded product in a downward direction against the running of the thermoplastic resin molded product. 1. A method for cooling a melt-extruded product, characterized in that the product is cooled by guiding the product into a cooling cylinder in which an upward flow is generated. (2) In a device that cools a thermoplastic resin molded product extruded vertically downward from a molding die, a vertically movable cooling cylinder is provided directly below the die, and a vertically movable cooling cylinder is provided below the cooling cylinder. The molded product is introduced into the water tank by passing through the cooling cylinder, and cooling water in which a surfactant is dissolved is provided in the cooling cylinder in a direction opposite to the running direction of the molded product. A cooling device for melt extruded products characterized by circulating supply.