JPS6239208A - Manufacture of raw polyester master polymer - Google Patents

Abstract

PURPOSE:To enable to manufacture a polyester master polymer which is obtained by dispersing a pigment highly uniformly and has a high concentration of pigment, by kneading with rotational power of specific magnitude by limiting a scope of the mixture ratio between polyester and the pigment at a first step. CONSTITUTION:At the first kneading step, it is necessary to set the mixture ratio between polyester and pigment at a weight ratio of 60:40-40:60. Kneading is performed further at the second step; it is desirable to set the concentration of pigment at this time at 10-40wt%. With this construction, the dispersability of pigment can be improved and it is possible to lower the temperature of the polyester raised through shearing force at the time of kneading at the first step and to control thermal decomposition. It is necessary to make rotational power at the time of the kneading more than 0.03kW per 1kg of a kneading thing. With this construction, at the low rotational power, dispersion of the pigment becomes insufficient because of lack of shearing force. However, it is wastefulness in energy to raise the rotational power excessively and the rotational power to the extent of 0.07-0.2kW is desirable.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing a spun-dyed polyester master polymer used in the production of pigment-containing fibers, films, etc. The present invention relates to a method for producing a doped polyester master polymer in which pigments are uniformly dispersed by kneading in two stages under specific conditions in a screw-type twin-screw kneading extruder.

(Prior Art) Polyester, especially polyethylene terephthalate or a polyester mainly composed of polyester, has a mechanical property.

As a material with excellent chemical performance, it is widely used as molded products such as fibers and films, but it is also often used as a spun-dyed polyester mixed with an R material.

When producing a molded product, it is common to prepare a master polymer containing a high concentration of pigment, add this to a base polymer that does not contain pigment, and then mold the product.

Methods for producing spun-dyed polyester include a method in which a pigment is added during polyester synthesis, and a method in which a polyester and a pigment are mixed in a Negoo mixer, a Banbury mixer, or the like. However, the former method is difficult to support high-mix, low-volume production.

The latter method has the problem that it is difficult or takes a long time to disperse the pigment highly uniformly in the polyester, especially when producing a master polymer with a high pigment concentration. It was difficult to do so.

In addition, JP-A No. 58-212908 discloses that when an additive such as a pigment is mixed into a molten polymer using a twin-screw kneading extruder, the polymer that is supplied in a fixed amount is divided into streams.

A method has been disclosed in which a portion of the polymer is mixed with additives and dispersed, and then the remaining polymer is merged downstream of a twin-screw kneading extruder. It manufactures fibers.

(Problems to be Solved by the Invention) In the present invention, the pigment is highly uniformly dispersed. The object of the present invention is to provide an easy method for producing a polyester master polymer with a high pigment concentration.

(Means for Solving the Problems) The present invention achieves the above object, and its gist is to knead polyester and pigment in two stages in a screw-type twin-screw kneading extruder to produce a spun-dyed polyester. When producing the master polymer, the mixing ratio of polyester and pigment in the first stage is set to a weight ratio of 60:40 to 40:60, and kneading is performed with a rotational power of 0.03 KW or more per Ikg of kneaded material. There is a method for producing a spun-dyed polyester master polymer.

In the present invention, the 5-rotation dynamic nozzle is the power consumption during kneading minus the power consumption during idle operation with no kneaded material, and is expressed as power consumption per Ikg of kneaded material.

In the present invention, the polyester supplied to the first-stage kneading section may be either a molten polyester discharged from a polycondensation reactor or a polyester once formed into a belent shape.

In the first-stage kneading section, it is necessary to set the mixing ratio of polyester and pigment to a weight ratio of 60:40 to 40:60. By increasing the pigment concentration, the viscosity in the molten state is increased and high shear forces are generated.

However, if the pigment concentration is too high.

The viscosity may become too high and fluidity may be lost, and the polyester may decompose due to the temperature rise inside the kneader extruder due to shearing force.1 Furthermore, troubles such as wear and seizure of the shaft and disk inside the kneader extruder may occur. occurs.

Further kneading is carried out in the second stage kneading section, and the pigment concentration at this time is preferably 10 to 40% by weight. Thereby, it is possible to improve the dispersibility of the pigment, and also to lower the temperature of the polyester, which has risen due to the shear force during the first stage of kneading, and to suppress thermal decomposition. Incidentally, if the pigment concentration is too low, it becomes unsuitable for use as a master polymer.

In addition, in the present invention, the rotational power during kneading is changed to the kneaded material I.
It is necessary to set it as 0.03KW or more per kg.

If the rotational power is lower than this, the shearing force will be insufficient and the pigment will not be sufficiently dispersed. However, increasing the power per revolution unnecessarily is a waste of energy, and it is 0.07 to 0.2
KW or so is preferable.

In the present invention, the polyester is typically polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate, and may also contain a modifier.

Further, as the pigment in the present invention, inorganic pigments and organic pigments with good heat resistance can be used. Specific examples of pigments include titanium dioxide, silica, carbon black, iron oxide, cadmium yellow, copper phthalocyanine blue, copper phthalocyanine green, polyazo pigments, quinacridone pigments, thren pigments, benzidine pigments, thioindigo pigments, and perylene. pigments, perinone pigments.

Examples include dioxazine pigments.

(Example) Next, the present invention will be specifically explained with reference to Examples.

In the examples, "parts" represent parts by weight per unit time.

Examples 1 to 7 and Comparative Examples 1 to 4 PET pellets with an intrinsic viscosity [η) of 0.6B and titanium dioxide (TiOz) II & powder were mixed at the mixing ratio shown in Table 1 using a screw-type twin-screw kneading extruder. The temperature of the kneading section was set at 270°C (285°C only in Comparative Example 1).

The mixture was continuously kneaded in two stages using the rotational power shown in Table 1, and pelletized to obtain master pellets.

Table 1 shows the results of evaluating the degree of pigment dispersion of this master pellet as follows.

(1) Melt 7 to 10 mg of master pellet pigment dispersion polymer on a glass slide,
A cover glass was placed on the sample, and the number of pigment particles of 10 parts or more was measured using a microscope and evaluated on the following four scales.

(Pass if A, B.) A: 1 pigment particle of 10 parts or more / 6 mg or less B: 10
(2) Contains back pressure increase rate master pellet and pigment PET pellets with no pigment were mixed so that the pigment concentration was 0.5%.

Melt spinning was carried out by a conventional method at a discharge rate of 35 g/min/spindle.

The spinneret bank pressure increase rate during continuous operation for 20 days was investigated.

Table 1 Example 8 Using a screw-type twin-screw kneading extruder, PET berent and carbon blank were mixed continuously in two stages with the temperature of the kneading section set at 270°C and the rotational power of the other end at 0.11°C. The mixture was kneaded and made into pellets to obtain a master pellet.

The mixing ratio of P E 'I' and carbon black was 1st stage: 75 parts of PE, 5 parts of carbon blank, and 20 parts of PET supplied in the second stage.

This master pellet and PET pellet that does not contain pigment 7
) were mixed so that the pigment concentration was 1.0% and melt-spun.

When the degree of dispersion of the pigment in the spun yarn was evaluated according to Example 1, the number of pigment particles of 20 parts or more was 3/6 mg.

The back pressure increase rate was 10%.

(Effects of the Invention) According to the present invention, a solution-dyed polyester master polymer in which a pigment is highly uniformly dispersed in polyester can be easily obtained. If this master polymer is used, especially when manufacturing fibers, the spinnability is good, pack pressure increase is suppressed, and high-quality spun-dyed fibers can be manufactured with good productivity.

Claims (1)

[Claims] (1) When kneading polyester and pigment in a screw-type twin-screw extruder in two stages to produce a spun-dyed polyester master polymer, the mixing ratio of polyester and pigment in the first stage was set to 60: 1. A method for producing a doped polyester master polymer, which comprises kneading at a weight ratio of 40 to 40:60 and at a rotational power of 0.03 KW or more per 1 kg of kneaded material.