JPS61246236A - Production of stock-dyed polyester pellet - Google Patents

Abstract

PURPOSE:To obtain the titled pellets in which a pigment can be highly uniformly dispersed and which is excellent in spinnability in high-speed spinning, by forming a master batch by melt-blending a polyester dry-blended with a pigment and melt-blending again this master batch with a polyester. CONSTITUTION:A master batch is prepared by dry-blending polyethylene terephthalate of a bulk density of 0.2-0.6g/cm<3> or a polyester based thereon with 30-60wt% inorganic pigment or an organic pigment of good heat resistance, such as TiO2 or metal phthalocyanine, and melt-blending the obtained dry blend. This master batch is melt-blended again with a polyester of an intrinsic viscosity >=0.5 in such an amount that the pigment concentration in the obtained pellets is 1-30wt% to obtain the titled pellets.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing sporadically dyed polyester pellets in which a pigment is mixed with polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate.

(Prior art) Polyethylene terephthalate or polyester mainly composed of polyethylene terephthalate is a material with excellent mechanical and chemical performance and is widely used for molded products such as fibers, films, and bottles. It is often used as a dyed polyester.

However, such polyesters have a high melting point and the degree of polymerization easily decreases when they come into contact with water or oxygen at high temperatures, so it is difficult to disperse pigments highly uniformly, especially when melt-spinning fibers. When producing this, there were problems in that the spinning filter would become clogged in a short period of time and the yarn would break frequently.

Various proposals have been made to solve these problems, but none have reached a fully satisfactory stage. for example,
In Japanese Patent Publication No. 49-9616, the bulk density is 0.3 g.
A method of mixing polyethylene terephthalate powder with a particle size of less than /cm3 and a pigment has been proposed, but simply mixing the polyester powder and the pigment does not allow use in high-speed spinning in which the pigment is highly uniformly dispersed. It is difficult to obtain dry-coated pellets.

(Problems to be Solved by the Invention) In the present invention, a pigment is mixed with polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate.

The object of the present invention is to provide a method for producing a spun-dyed polyester pellet in which the pigment is highly uniformly dispersed, there are no agglomerates, and the spinnability is excellent even in high-speed spinning.

(Means for Solving the Problems) The present invention achieves the above objects, and the gist thereof is as follows.

When producing a spun-dyed polyester pellet made by mixing 1 to 30% by weight of a pigment with polyethylene terephthalate or a polyester mainly composed of polyethylene terephthalate.

First, a pigment is dry-blended into polyester with a bulk density of 0.6 g/cm3 or less, and then melt-blended to prepare a masterbatch with a pigment concentration of 30 to 60% by weight. 1. A method for producing a spun-dyed polyester pellet, which comprises melt-mixing the polyester and polyester again at a ratio that provides a predetermined pigment concentration.

In the present invention, the bulk density of polyester is JISK 6
911, and the intrinsic viscosity is a value measured at 20° C. using a mixture of phenol and tetrachloroethane at a weight ratio of 3/2 as a solvent.

When carrying out the method of the present invention, first, the bulk density is 0.
After dry-blending polyester of 6 g/cm or less and a predetermined amount of pigment in a double cone blender, V-type blender, Henschel mixer, roll-type blender, pressurized Nigoo, Banbury mixer, etc. at a temperature lower than the melting point of the polyester, A masterbatch is prepared by melt-mixing (secondary mixing) using a pressurized Nigu, Banbury mixer, etc. at a temperature higher than the melting point of polyester. Next, this masterbatch is dried to a water content of 1,100 pp or less, and then melt-mixed (secondary mixing) with a polyester having an intrinsic viscosity of 0.5 or more at a ratio that provides a predetermined pigment concentration.

For secondary mixing, use a kneader with a shaft or two or more wheels.

It is preferable to use a model that has measures for improving the kneading effect on the shaft and/or barrel.

-The bulk density of the polyester used for the next mixing is 0.6 g/c
It is necessary that the bulk density is less than m3, and if the bulk density is larger than this, the dry breading effect will be substantially lost and it will not be possible to obtain pellets in which the R material is highly uniformly dispersed. However, it is not preferable that the bulk density is too small, such as 0.2 g/cm' or less. Such a polyester having a low bulk density is difficult to prepare and only reduces the throughput of the mixing equipment, so that it cannot be expected to significantly improve the degree of pigment dispersion.

Polyester having a bulk density of 0.6 g/cm' or less can be obtained as dust generated during the process of crushing solid polyester or drying polyester pellets.

Further, as the pigment in the present invention, inorganic pigments and organic pigments with good heat resistance can be used. A specific example of a pigment is carbon black.

Examples include titanium dioxide, colloidal silica, and metal phthalocyanine.

During primary mixing, the pigment concentration of the masterbatch is 30
It is necessary to adjust the amount to 60% by weight. If the pigment concentration exceeds 60% by weight, it becomes mechanically difficult to prepare a masterbatch, and even after secondary mixing, pellets in which the pigment is highly uniformly dispersed cannot be obtained. On the other hand, when the pigment concentration is less than 30% by weight, the amount of polyester whose intrinsic viscosity has decreased due to water caused by the pigment increases, and even when mixed with polyester with a high degree of polymerization in the secondary mixing, the decrease in the intrinsic viscosity is covered. As a result, pellets with the desired intrinsic viscosity cannot be obtained.

Further, it is necessary that the final pellet has a pigment concentration of 1 to 30% by weight. If the pigment concentration exceeds 30% by weight, the pellet becomes brittle, which not only increases the generation of dust during handling, but also makes it difficult to disperse the pigment highly uniformly.On the other hand, when the R pigment concentration exceeds 1% by weight,
If less than

However, it is economically disadvantageous to employ the method of the present invention in which mixing is performed in two stages as in the present invention (although the pigment can be uniformly dispersed).

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

The polyester used in the examples was prepared as follows.

Polyester A After pulverizing polyethylene terephthalate undrawn yarn (to which no oil agent or the like is attached) using a CV-30 type pelletizer manufactured by Condax.

By compressing and fixing, and recycling the dust generated during the crushing process to the compression and fixing process, the intrinsic viscosity is 0.62. Polyester pellets having a bulk density of 0-56 g/cm3 were obtained.

Polyester B An undrawn polyethylene terephthalate yarn (to which no oil or other substances are attached) is crushed to obtain an intrinsic viscosity of 0.63. A polyester powder with a bulk density of 0.30 g/-cm3 was obtained.

Polyester C When preparing Polyester A, the dust generated in the crushing process was not recycled to the compression and fixing process, and the intrinsic viscosity was 0.62. Polyester pellets having a bulk density of 0.44 g/cm' were obtained.

Polyester D The dust generated when drying polyethylene terephthalate pellets is collected and has an intrinsic viscosity of 0.64. A polyester with a bulk density of 0.22 g/cm3 was obtained.

Polyester E Polyethylene terephthalate pellets in the shape of an elliptical cylinder with a major axis of 4 m +, a minor axis of 2 m, and a length of 4 fi were immersed in liquid nitrogen, and then frozen and ground in the presence of liquid nitrogen using a Micron Victory Mill manufactured by Hosyo Micron Co., Ltd. .

Intrinsic viscosity is 0.63. A polyester powder with a bulk density of 0.16 g7 cm' was obtained.

Polyester F Polyethylene terephthalate obtained by melt polycondensation by a conventional method is paid out in the form of a strand, cooled, and then cut to give an elliptical columnar shape with a major axis of 4 m, a minor axis of 2 tm, and a length of 4 cranes, and an intrinsic viscosity of 0.64. Polyester pellets with a bulk density of 0.84 g/cm'' were obtained.

Polyester G Polyethylene terephthalate obtained by melt polycondensation by a conventional method is paid out in a sheet form and cooled.

When cut, it has a rectangular parallelepiped shape with length and width of 4 m, height of 2 m, and an intrinsic viscosity of 0.63. Bulk density is 0.73 g/c
m'' polyester pellets were obtained.

Example 60 parts by weight of each of the polyesters A to G and 40 parts by weight of carbon black MA-600 manufactured by Mitsubishi Chemical Industries, Ltd. were dry-blended using an FM-10B model Henschel mixer manufactured by Mitsui Miike Kakoki Co., Ltd., A master bunch was prepared by melt-mixing using a 3-5 type pressurized knee gun manufactured by Moriyama Seisakusho.

Next, this master bunch was continuously fed at a rate of 25 parts by weight/hour and polyester F at a rate of 25 parts by weight/hour to a ZCM41/46 type twin-screw kneader manufactured by Automatic Co., Ltd., and melt-mixed to form spun-dyed polyester pellets. Obtained.

The obtained pellets were diluted 10 times with polyester F, sandwiched between two glass plates, heated and melted, and after rolling,
Using a 0x microscope, the number of coarse particles with a diameter of 13 μm or more in 6 mg of the sample was measured to evaluate the dispersion state of carbon black.

The results are shown in Table 1.

Table 1 Note: Dimensions 6 and 7 are comparative examples.

Next, the solution-dyed pellets obtained by the above method were mixed with a moisture content of 30p.
After drying to below pm, the undyed pellets were fed at a rate of 1.25 parts by weight/hour and the polyester F at 48.5 parts by weight/hour to an extruder type melt spinning apparatus having a screw with a diameter of 45 m.

Filtered through an 800 mesh filter, melt-spun, and
It was wound up at a speed of 500 m/min.

Table 2 shows the results of examining the time (filter life) from the start of spinning until continuous spinning becomes impossible due to an increase in filtration pressure and the number of yarn breakages during that time.

Table 2 (Effects of the Invention) According to the present invention, pigments are highly uniformly dispersed in polyethylene terephthalate or a polyester mainly composed of polyester, and there are no agglomerates, and the material exhibits excellent spinnability even in high-speed spinning. It becomes possible to produce coated polyester pellets.

Claims (1)

[Claims] (1) When producing spun-dyed polyester pellets in which 1 to 30% by weight of pigment is mixed with polyethylene terephthalate or polyester mainly composed of polyethylene terephthalate, first, the pigment is driven into polyester with a bulk density of 0.6 g/cm^3 or less. After red, melt blend to a pigment concentration of 30 to 60.
% by weight of a masterbatch, and then melt-mixing this masterbatch and a polyester having an intrinsic viscosity of 0.5 or more again in a ratio that provides a predetermined pigment concentration.