JPS6147229A - Cooling method of strand - Google Patents

Abstract

PURPOSE:To contrive to solve the troubles of adhesion of additive agent to cooling duct and of the resultant breaking of strand by a method wherein hot water, the amount of which is enough for a portion of running strand to soak in, is flowed in some part of the cooling duct. CONSTITUTION:Hot water is flowed in at least some part of cooling duct in the method to cool and solidity thermoplastic resin strand melt-extruded from a die by running it in the cooling duct. The amount of hot water is enough for some portion of the cross-section of the strand or of the cross-section normal to the running direction of the strand to soak in, preferebly for the lower half portion of the cross-section of the strand to soak in. The temperature of the hot water is preferably as high as possible within the range, in which the take-up force applied to the strand and the tension due to the weight of strand itself do not produce the excessive stretching or breaking of the strand. Because the hot water existing between the duct and the strand acts as lubricant, low compatible or subliming addition agent either adheres to the surface of the strand or flows by scattering in the hot water, resulting in causing no hindrance for the running of the strand due to the adhesion to the duct.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of cooling a melt-extruded thermoplastic resin strand, and more particularly to a method of cooling a strand by flowing hot water through cooling channels.

[Prior art]

In general, various compounds are added to thermoplastic resins for the purpose of imparting or improving their stability, moldability, and other properties.

However, some of these additives have poor compatibility with thermoplastic resins, and others increase their susceptibility at high temperatures.

Thermoplastic resin is usually used for molding as a molding material called pellets, chips, etc., but such molding material is, for example, melted and extruded from a die to form a strand, run through a cooling a, cooled and solidified, Furthermore, it is manufactured by cutting it into a predetermined length. In this case, if the thermoplastic resin contains the above-mentioned additives, these may leach out and sublimate from the resin and adhere to the cooling grooves, inhibiting the running of the strands, and as a result, causing the strands to break. This was an obstacle to smooth production.

[Purpose of the invention]

An object of the present invention is to provide a strand cooling method that eliminates the adhesion of additives to the grooves and the resulting breakage of the strands.

[Structure of the invention]

The present invention provides a method for cooling and solidifying thermoplastic resin strands melted and extruded from a die by running them through cooling grooves, in which hot water is flowed in an amount such that a part of the running strands is immersed in at least a part of the wave grooves. This is a strand cooling method characterized by the following.

The thermoplastic resin used in the present invention is characterized by its stability,
It contains additives for imparting and improving moldability and other properties. A specific thermoplastic resin is polyethylene.

Examples include polypyrene, polymethyl pentene, polyvinyl chloride, polystyrene, poly(meth)acrylate, polyester, polycarbonate, boria ξ, polyphenylene ether, and copolymers thereof.

The additives blended into the thermoplastic resin in the present invention are compounds added for the purpose of imparting/improving the stability, moldability, and other properties of the thermoplastic resin, and are added by melt-extruding the resin containing the additives. This is a compound that has the property of adhering to the cooling grooves when the strands run through the cooling grooves. Some of these additives include those that have poor compatibility with aJ resin and release Ka after melt molding, and others that sublime from the resin because they are sublimable under extrusion conditions. Examples of these additives include compounds having aromatic rings and heteroartic rings with or without substituents such as halogens, hydroxyl groups, and 7-mino groups, and derivatives of unsaturated fatty acids.

Cooling grooves are for running and cooling the strands,
For example, the lower surface of a corrugated plate having a Vm or U-shaped cross section can be cooled with a cooling medium such as water, and a metal one can preferably be used. The melt-extruded strands run in these grooves, and it is desirable to have one strand run in each groove to avoid fusion of the strands.

In the present invention, hot water is allowed to flow through at least a portion of the cooling groove. The amount of hot water is such that a part of the strand's cross section, that is, a part of the cross section perpendicular to the running direction, is immersed, and it is preferable that the lower half of the strand is immersed. If the amount of hot water is greater than that, the strands will float up in the grooves, meandering, and become twisted, and if they become brittle in this state, subsequent handling becomes difficult. It is preferable to set it as high as possible within the range where the strand is not excessively stretched or cut due to the tension due to the pulling force and its own weight. to be cooled by
This results in a zigzag INK, which makes subsequent handling troublesome, and also creates vacuum bubbles in the strand, which is undesirable in terms of appearance and strength. Specifically, it is determined by the thermoplastic resin, equipment, and method used. For example, in polycarbonate resin, 70 to 90°0
It is preferable to supply hot water of 500 ml to the cooling groove.

In the present invention, a preferred method for flowing hot water into the cooling groove is to create a flow of hot water from one end of the groove to the other end;
This is a method of flowing in the same direction as the running direction of the strands.

According to the method of the present invention, the warm water existing between the groove and the strand acts as a lubricant, so that the additive with low compatibility or sublimability will adhere to the surface of the strand, or
Since it flows dispersedly in the warm water, it does not adhere to the grooves and impede the running of the strands.

〔Effect of the invention〕

According to the method of the present invention, as described above, the cooling and assimilation of the strands is carried out extremely smoothly, and the resulting stride is only a short distance 9, so that, for example, even if the cutting and pelletizing process is connected to the cooling process, , pelletization can be carried out smoothly without any tangles.

〔Example〕

The present invention will be explained in detail with reference to Examples below.

Example: Hot water discharge holes were installed in the grooves of the corrugated plate directly below the nozzle of the extrusion device, which had a corrugated plate-shaped cooling surface gently sloping downward from a position approximately 25 cm below the nozzle. While cooling with water, hot water of about 80'O was discharged from the hot water discharge hole and flowed into the grooves of the corrugated plate.

Approximately 1 ff of 2-(2-hydroxy-5-methyl-phenyl)-2H-benzotriazole as light stabilizer for extrusion
A polycarbonate powder with an average molecular weight of 22,000, admixed with % iflc, was fed and extruded through a nozzle at approximately 280° so that the strands ran through the grooves. The temperature of the hot water flowing through the grooves is approximately 65°0.0 near where the strand contacts the grooves. It was about 40'O when the strand completely cooled and solidified and left the groove, and at this time the strand was about 115'O.

This operation continued for 8 hours, but the operation went smoothly without any additives adhering to the grooves, and the obtained strands were straight without scratches, wrinkles, meandering, or air bubbles.

COMPARATIVE EXAMPLE The operation was carried out in the same manner as in the example except that hot water was not flowed in the apparatus of the example. As time progressed, the additive that sublimated into the grooves became sticky white, and after about 2 hours, the strands no longer ran smoothly, and after 1 minute, they were cut. The additive was partially attached to the surface of the obtained strand, and scratches were also generated.

Claims (1)

[Claims] A method of cooling and solidifying a thermoplastic resin strand melted and extruded from a die by running it through a cooling groove, characterized by flowing hot water in an amount such that a part of the cross section of the running strand is immersed in at least a part of the groove. How to cool the strands.