JPH0570567A - Polyester chips - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a polyester chip that has been subjected to solid phase polymerization in which the fluidity and the like during homogenization are homogenized. Providing polyester materials suitable for tire cords (fibers) and bottles. [Structure] If the intrinsic viscosity is increased by at least 0.15 with respect to the prepolymer by solid-state polymerization, the intrinsic viscosity and the density of the polyester chip will be different. Therefore, the intrinsic viscosity difference between the inner and outer layers should be 0.125 or less. , And the density difference is 0.
When it is 0019 or less, uniformity during melt molding is maintained,
Moldability is stable (improved).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester solid-state polymerized chip, which can be easily melted in melt molding such as extrusion molding or injection molding of fibers, films, bottles, etc. Regarding polyester chips.

[0002]

BACKGROUND OF THE INVENTION Polyester is widely used in fibers, films, bottles, industrial resins and the like because of its excellent mechanical, physical and chemical properties.

[0003] Among these, in a field requiring moisture and heat resistance such as a tire cord and a dryer canvas, a low carboxyl content is obtained, and in a field requiring high strength such as a sewing thread and a tire cord, a high intrinsic viscosity is obtained. for,
In order to reduce oligomerization in the field where low scum is required in the film for electrical insulation and in the manufacturing process, in order to reduce acetaldehyde in fields where taste and odor of carbonated beverages etc. are a problem, various other Generally, solid-state polymerization is often performed for the purpose. However, solid phase polymerization raises the temperature of the polymer by heating from the outside, and water, glycol and other low molecular weight compounds generated as a result of the reaction are diffused and removed from the surface to the outside of the reaction. Inevitably, in one chip, a quality difference occurs between the inner layer (core portion) and the outer layer (near the surface) of the chip. For example, the intrinsic viscosity is higher in the outer layer, and the density is higher in the inside, probably because the heat of crystallization accumulates inside.

There is no particular problem in the case of melt molding under normal conditions, but as the melt molding speed is increased to improve the productivity during molding, the difference in the melting behavior due to the difference between the inner and outer layers of the chips gradually increases. And the physical properties of molded products will be affected.

In order to prevent this, although the melting temperature is raised or a heating hopper is provided so as to raise the chip temperature before entering the molding machine, since the polymer is melted unduly. However, there is a limit to the productivity because the polymer is partially decomposed and the quality of the molded product becomes uneven.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a polymer chip which is easily melted so that the moldability and the quality of the molded product are not deteriorated even at high speed melt molding.

[0007]

According to the present invention, in a polyester chip having an intrinsic viscosity increased by at least 0.15 by a solid-state polymerization method, the intrinsic viscosity difference between the outer layer and the inner layer is 0.125 or less, and the density thereof is The difference is 0.0019
It is a solid phase polymerization chip of polyester which is required to be the following.

In the present invention, the "polyester" means a polyester having an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component.
Here, "mainly" means that dicarboxylic acid and glycol are 8
It means that it occupies 5 mol% or more. A technique containing 15 mol% or less of the third component is a technique to which the present invention can be applied.

Examples of the "aromatic dicarboxylic acid" constituting the polyester include terephthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketonedicarboxylic acid and diphenoxyethanedicarboxylic acid.

Examples of the "aliphatic glycol" constituting the polyester include ethylene glycol, trimethylene glycol, tetramethylene glycol and hexamethylene glycol.

The third component which can be copolymerized is an aromatic dicarboxylic acid constituting the polyester, a dicarboxylic acid other than an aliphatic glycol, a diol or an oxycarboxylic acid. Specifically, in addition to the above compounds, aromatic dicarboxylic acids such as isophthalic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, sodium-sulfoisophthalic acid, dibromoterephthalic acid, etc .;
Examples thereof include alicyclic dicarboxylic acids such as decalin dicarboxylic acid, tetralin dicarboxylic acid and hexahydroterephthalic acid; and aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid and sebacic acid. or,
As the glycol component, an aliphatic diol such as pentamethylene glycol, diethylene glycol, triethylene glycol, etc .; an aromatic diol such as catechol, naphthalene diol, resorcin, 4,4 ′
-Dihydroxy-diphenyl-sulfone, bisphenol A [2,2'-bis (4-hydroxyphenyl) propane], tetrabromobisphenol A, bishydroxyethoxybisphenol A; alicyclic diol, cyclohexanediol, etc .; fat Group oxycarboxylic acids such as glycolic acid, hydroacrylic acid,
3-oxypropionic acid, etc .; alicyclic oxycarboxylic acid, such as asiatic acid, quinobaic acid, etc .; aromatic oxycarboxylic acid, such as salicylic acid, m-oxybenzoic acid, p-oxybenzoic acid, mandelic acid, atrolactic acid, etc. Can be mentioned.

Further, within the range where the polyester is substantially linear, a polyfunctional compound having a valence of 3 or more, such as glycerin, trimethylolpropane, pentaerythritol,
Trimellitic acid, trimesic acid, pyromellitic acid, tricarbamic acid, gallic acid, etc. may be copolymerized, and if necessary, a monofunctional compound such as o-benzoylbenzoic acid,
Naphthoic acid or the like may be added.

Further, if necessary, an abrasion agent, a flame retardant, a flame retardant aid, an antioxidant, an ultraviolet absorber, a pigment, a dye, a lubricant, a crystallization nucleating agent, a crystallization accelerator, a reinforcing material, etc. are contained. It may be one.

The prepolymer before the solid phase polymerization of the polyester of the present invention can be produced by a generally known method. For example, after directly esterifying acid and glycol,
Examples thereof include a method of melt polycondensation in the presence of a suitable catalyst, a method of melt polycondensation after transesterification of a lower alkyl ester of an acid and glycol in the presence of a suitable catalyst. In both cases, melt extrusion after melt polycondensation,
It is cooled in a suitable catalyst such as water, cut into a suitable size and made into chips. The chips may be rectangular parallelepiped, cylindrical, dice or spherical.

In the polyester of the present invention, the polymer thus obtained is further subjected to solid phase polymerization at a temperature below the melting point to increase the intrinsic viscosity by 0.15 or more until it reaches a desired value.

When the difference in intrinsic viscosity before and after the solid phase polymerization is 0.15 or more, the difference from the conventional method becomes clear and the effect becomes remarkable.

The solid phase polymerization in the present invention may be carried out under an inert gas flow or under vacuum (under reduced pressure), and may be applied in a continuous system or a batch system. Further, it may be a packed tower type, a horizontal clinker type, or a tumbler type.

In the present invention, it is required that the difference in intrinsic viscosity between the outer layer and the inner layer of the chip after solid state polymerization is 0.125 or less and the difference in density thereof is 0.0019 or less. The intrinsic viscosity difference is preferably 0.120 or less and the density difference is 0.0018.
It is below.

In the present invention, the "outer layer" refers to the area within 0.5 mm from the outer surface of the chip. The "inner layer" is from the center of the chip to the outside 0.3 mm. The outer layer is cut out from several chips and the inner layer is cut into inner layers, and the intrinsic viscosity and density are measured. When solid-phase polymerization is carried out by the usual method, the difference in intrinsic viscosity between the inner and outer layers is 0.15 to 0.2, depending on the shape of the chip and solid-state polymerization conditions.
5, the density difference is 0.0020 to 0.0030.

To treat the difference in the intrinsic viscosity and the density between the inner and outer layers in the chip within the range of the present invention, the following method is exemplified. (1) Reduce the chip shape. For example, the equivalent spherical diameter should be 2.8 mm or less. (2) To reduce the chip thickness, for example, in the case of a rectangular parallelepiped or a cylinder, the thickness or width is set to 1.8 mm. (3) Keep the solid phase polymerization temperature low. For example, in the case of polyethylene terephthalate, the temperature is 215 ° C. or lower. (4) The carrier gas flow rate used in the solid-state polymerization reaction is suppressed to, for example, 1 m / sec or less in superficial velocity. (5) In the crystallization step prior to solid-phase polymerization, the carrier gas flow rate is increased so that the crystallization heat does not accumulate heat. (6) When performing solid-phase polymerization stepwise, keep the initial temperature as low as possible. (7) The inside of the chip is uniformly heated by microwave heating. If these cannot achieve the purpose by one method, it is necessary to combine a plurality of means.

[0021]

EFFECTS OF THE INVENTION The solid phase chip according to the present invention has a small difference in quality between the inner and outer layers, does not cause non-uniform melting and non-uniform flow even in high-speed melt molding, and provides stable moldability and molded product quality.

[0022]

EXAMPLES The present invention will be supplemented by the following examples. In addition, "part" in an Example means a weight part. Moreover, the measuring method of the characteristic used in the Example is shown below. 1) Intrinsic viscosity: [η] phenol / tetrachloroethane (weight ratio 60/40)
It was calculated from the melt viscosity measured at 35 ° C using the mixed solvent of. 2) Density: The density at 25 ° C was measured in a density gradient tube of n-heptane / carbon tetrachloride system.

Polymer Production Example Using a cylindrical polyethylene terephthalate chip having an intrinsic viscosity of 0.55 dl / g shown in Table 1, solid phase polymerization was carried out under various conditions by using a continuous model clinker type solid phase polymerization equipment. Solid-state polymerization chips with different quality of inner and outer layers were obtained.

Polymer A is a conventional type having both intrinsic viscosity difference and density difference outside the scope of the present invention, polymer C is suitable for high-speed molding in which both are within the scope of the present invention, and polymer B or D is either One is outside the scope of the present invention.

[0025]

[Table 1]

[0026]

Example 1 30 mm with polymers A, B, C and D
Diameter extruder, cylinder temperature 290 ℃
Was spun at a discharge rate of 50 g / min. Since spinning was possible for 4 hours without any problem, spinning was then carried out with the screen rotation speed increased and the winding speed increased to 1.5 times at a discharge speed of 75 g / min. Polymers A and B showed throat pressure fluctuations. Was large, and A was broken at 1 hour and B was broken at about 2 hours. C and D could be spun for 4 hours without yarn breakage, but D
The yarn from this polymer had large denier mottle.

[0027]

Example 2 Using Polymers A, B, C and D, 105
Bottle molding was carried out using an injection molding machine having a screw with a diameter of mm and using 48 preform molds. At the beginning, a 40 second cycle (72 lines / minute) was started, and the molding speed was increased every hour. Polymer A had a charge fluctuation at the 33 second cycle (87 lines / minute), and a flow pattern appeared at the mouth of the preform. Polymer B exhibited the same phenomenon when it was cycled for 30 seconds (96 lines / minute). Polymers C and D could be molded stably without any abnormality up to a 27-second cycle (107 lines / minute). However, the preform made of the polymer D was partially sinked when the mouth was crystallized.

Claims (1)

[Claims] 1. In a polyester chip having an intrinsic viscosity increased by at least 0.15 by a solid-state polymerization method, the difference in intrinsic viscosity between the outer layer and the inner layer of the chip is 0.125 or less, and the difference in density is 0. Polyester chip that has undergone solid-state polymerization, characterized in that it is below 0019.