JPH1077393A - Production of polyester composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the obtaining of the subject composition excellent in particle dispersibility, moldability and quality of a molding product by feeding a polyester and a slurry of inorganic particles and/or organic particles from the same raw material feed port to a vented type twin-screw extruder. SOLUTION: (A) A substantially undried polyester and (B) a slurry of inorganic particles and/or organic particles substantially containing water as a medium from the same raw material feed port to a vented type twin-screw extruder to thereby afford the objective polyester composition. Concretely, e.g. polyethylene terephthalate having 0.650(dL/g) intrinsic viscosity and 0.2wt.% moisture content and an aqueous slurry containing 15wt.% fine silica are fed from the same raw material feed port to the vented twin-screw extruder having 44mm cylinder diameter to carry out the melt extrusion of the polyester composition. Thereby, the particles can be added with high constant rate properties and the composition such as extremely low deterioration in intrinsic viscosity of the polyester can be expected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polyester composition, and more particularly, to a method for producing a polyester composition containing inorganic particles and / or organic particles using a vented twin-screw extruder. It is about the method.

[0002]

2. Description of the Related Art Polyesters represented by polyethylene terephthalate and polyethylene naphthalate are widely used as raw materials for films, bottles, fibers, and other various molded products because of their excellent chemical and physical properties. In particular, biaxially oriented polyester films represented by polyethylene terephthalate have excellent mechanical properties, electrical properties, chemical resistance, dimensional stability, etc.
Information recording materials, capacitors, packaging, plate making, electrical discharge,
It is used as a substrate in many fields such as photographic film.

By the way, in order to satisfy processing suitability and required quality according to the application, fine particles and pigments are added to polyester. For example, in the case of a polyester film for packaging, the slipperiness of the film is important in order to ensure workability when winding the film into a roll. As a method for imparting slipperiness to a film, a method is employed in which the film contains inorganic particles and / or organic particles to form minute projections on the film surface.

As a method of blending particles with polyester, a method of adding and dispersing particles during the polymerization of polyester is known. However, in the method of adding particles at the time of polymerization, it is difficult to apply high shear inside the reaction vessel, so that poor dispersion occurs and coarse particles are generated. Since the internal polyester composition cannot be completely removed, there is a problem that foreign matter is mixed in with the residual matter.

Japanese Patent Application Laid-Open No. Hei 6-91635 discloses a method for producing a polyester composition using a vent-type molding machine (a twin-screw extruder) in order to address the above-mentioned problems. A slurry of inorganic particles and / or organic particles is added, and immediately after the addition of the slurry, the polyester is retained and substantially melted, and the medium of the slurry is vaporized to be provided upstream of the slurry addition position. There has been proposed a method of removing through a vent hole.

Mixing of solids and liquids (including slurries) using a vented twin-screw extruder is a known technique, in which a liquid addition nozzle is generally provided at one or both positions before and after the vent. The provided vent type twin screw extruder is used. FIG. 2 is a side view of a vented twin-screw extruder used in a conventionally known manufacturing method described in JP-A-6-91635. In FIG. Machine), (2) is a heating cylinder, (3) is a screw,
(4) is an extrusion port, M is a screw driving device, (5) is a polymer inlet, (6) and (6 ') are vent holes,
(7) represents a slurry addition port, and (8) and (8 ') represent reverse screws.

The production method described in the above publication is an improvement of a method using a vented twin-screw extruder provided with a liquid addition nozzle, in which a slurry is added to polyester moving in a vented twin-screw extruder. This is a method in which the polyester is added, that is, the polyester is substantially completely dissolved immediately after the addition of the slurry, thereby shortening the kneading time between the polyester and the slurry to suppress the decrease in the viscosity of the polyester.

Therefore, in the above-mentioned manufacturing method, a reverse screw (8) as a retaining means is provided near the slurry addition port (7). Also, the medium of the slurry is removed through the vent hole (6) provided on the upstream side from the position where the slurry is added after being vaporized, but the vent hole (6) can be formed as long as the polyester does not vent up. As far as possible, it is preferred to provide the screw close to the reverse screw (8). In addition, 90 of the slurry medium
% Or more is preferably removed from the vent hole (6). In addition, slurry is supplied from the slurry addition port (7) provided between the vent hole (6) and the reverse screw (8), that is, in a region where the pressure of the slurry medium is high due to vaporization. It is said that it is preferable to apply a pressure so as to overcome the vapor pressure in the heating cylinder (2) and to perform addition and mixing. However, the above manufacturing method has various disadvantages as follows.

(I) Aggregation and destruction of the particles dispersed in the slurry occur due to strong shearing force generated in the slurry pressure pump. As a result, the dispersibility of the particles in the polyester deteriorates, or dispersed particles having a desired particle size cannot be obtained, and it is difficult to produce a polyester composition of good quality.

(Ii) It is difficult to supply a small amount of slurry quantitatively under high-pressure conditions, and as a result, the particle concentration in the polyester composition tends to fluctuate. Such problems are also exacerbated by the following rapid vaporization of the slurry medium. That is, the temperature of the slurry supplied at a high pressure is necessarily higher than the boiling point of the medium, and most of the medium is supplied from the vent hole (6) provided near the slurry addition port (7). To be removed, the slurry medium is rapidly vaporized in the heating cylinder (2).

(Iii) Since the slurry is added immediately before the polyester is melted, the steps before the plasticization of the polyester cannot be used for contact with the slurry, and the mixing efficiency is low.

(Iv) Immediately after the addition of the slurry, the polyester is substantially completely dissolved to shorten the kneading time between the polyester and the slurry so as to suppress the decrease in the viscosity of the polyester. Since the screw (8)) and the vent hole (6) for removing the medium of the slurry are close to each other, it is difficult to completely remove the medium depending on the reduced pressure conditions applied to the vent hole (6). The remaining medium is removed from the vent hole (6 '). Therefore, when the medium of the slurry is water, the polyester is hydrolyzed to lower its intrinsic viscosity.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polyester composition containing inorganic particles and / or organic particles using a vented twin-screw extruder. A method for producing a polyester composition, in which particles can be added with high quantitativeness, and the decrease in the intrinsic viscosity of the polyester is extremely small, and the particle dispersibility, moldability, and the quality of molded articles are excellent. Is to provide.

[0014]

That is, the gist of the present invention is to provide a method for producing a polyester composition containing inorganic particles and / or organic particles. A method for producing a polyester composition, comprising supplying a slurry of inorganic particles and / or organic particles.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a side view illustrating an example of a vent-type twin-screw extruder used in the production method of the present invention. In FIG. 1, (1) is a molding machine (extruder), (2) is a heating cylinder, 3) is a screw, (4) is an extrusion port, M is a screw driving device, (6) is a vent hole, (8) is a reverse screw,
(9) represents a polymer and slurry inlet.

The polyester used in the present invention refers to a polyester comprising an aromatic dicarboxylic acid component and a glycol component. In particular, 80% or more of the repeating units are ethylene terephthalate units or ethylene-2,2.
Polyesters having 6-naphthalate units or 1,4-cyclohexylene dimethylene terephthalate units are preferred. The polyester may have another third component copolymerized.

The aromatic dicarboxylic acid component includes:
Besides terephthalic acid and 2,6-naphthalenedicarboxylic acid, for example, isophthalic acid, phthalic acid, adipic acid,
Sebacic acid, 4,4'-diphenyldicarboxylic acid, oxycarboxylic acid (for example, p-oxyethoxybenzoic acid and the like) and the like. On the other hand, examples of the glycol component include, in addition to ethylene glycol and 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, neopentyl glycol, and the like. In the present invention, a polyester in which 80% or more of the repeating units are ethylene terephthalate units or ethylene-2,6-naphthalate units is suitably used.

In the present invention, examples of the inorganic particles include inorganic pigments such as silica oxide, calcium carbonate, titanium oxide, aluminum oxide, barium sulfate, lithium fluoride, kaolin, and iron oxide. , A divinylbenzene polymer, a copolymer of styrene and divinylbenzene, various ion exchange resins, and organic pigments such as anthraquinone. The type is not particularly limited as long as the particles can be supplied as a liquid slurry.

In the present invention, the slurry medium is
Water and ethylene glycol are preferably used. The type of the liquid is not particularly limited as long as the liquid is a liquid which does not cause a decrease in the intrinsic viscosity of the polyester due to vaporization when the polyester is melted or vaporization due to the reduced pressure at the vent portion. In addition, as a method for dispersing the inorganic particles and the organic particles in the medium, a known method using ultrasonic waves or shear stress can be employed.

In the present invention, the polyester and the slurry are supplied to the same raw material supply port of the vent type twin screw extruder. Specifically, the polyester and the slurry are supplied from the polymer and slurry inlet (9) shown in FIG. The supplied polyester and slurry are fed into a heating cylinder (2) by means of a screw (3) and an extrusion port (4).
It is transported toward. During that time, the slurry receives heat from the heating cylinder (2) and heat generated by the shearing action and evaporates. As a result, the heating cylinder (2)
Medium pressure increases. Then, the medium of the slurry is vaporized before the polyester reaches the reverse screw (8) and becomes a semi-molten state, and is discharged from the polymer and slurry inlet (9). If diffusion of the vaporized medium to the surroundings poses a problem, a suction / discharge device for the vaporized medium may be provided.

The polyester is transferred from the reverse screw (8) to the vent hole (6) and is degassed by the depressurizing action of the vent hole (6). In addition, in this specification, deaeration means
When substantially undried polyester is used, it means that moisture is diffused and removed from the surface of the molten polyester. As a result, a decrease in viscosity due to hydrolysis of the polyester is minimized. Polyester is
After being degassed in the vent hole (6), it is extruded from the extrusion port (4). If necessary, a vent hole may be further provided between the extrusion port (4) and the vent hole (6). . The heating cylinder (2), as is done in a normal extruder
By adjusting the temperature of the polyester composition, the temperature of the extruded polyester composition can be appropriately maintained.

The gist of the present invention is that the polyester and the slurry are supplied from the polymer and the slurry inlet (9) so that the slurry can be supplied at normal pressure or low pressure, and the slurry is supplied until the polyester is plasticized. The point is that the contact time between the polyester and the slurry is lengthened. Therefore, the polymer and slurry inlet (9) should have a size within 1D length (D is the inner diameter of the extruder) in the axial direction.

The temperature of the slurry supply section of the heating cylinder (2) is usually not higher than 200 ° C., preferably not higher than the boiling point of the slurry medium, and more preferably not higher than the boiling point of the medium.
The temperature is set to 0 ° C. or lower. However, in order to effectively vaporize the medium from the start of slurry supply, the lower limit of the temperature of the slurry supply section of the heating cylinder (2) usually needs to be about 60 ° C.

In the present invention, since the vaporization of the slurry medium is started from the point when the slurry is supplied to the raw material supply port,
It is possible to remove the medium substantially completely before the plasticization of the polyester, i.e. before reaching the reverse screw (8). Therefore, suitable water can be used as a medium for the slurry, and water up to 10% by weight relative to the polyester can be used. If the proportion of water exceeds 10% by weight, the amount of water vapor removed from the polymer and slurry inlet (9) becomes too large, making it difficult to supply new polyester and slurry.

In the present invention, the polyester is transferred to the vent hole (6) after the slurry medium is removed as described above. Then, when a substantially undried polyester is used, the moisture inside the polyester is degassed by the depressurizing action from the vent hole (6). In order to increase the degassing efficiency of water, the degree of pressure reduction of the vent hole (6)
Usually 40 mmHg or less, preferably 30 mmHg or less,
More preferably, it is 10 mmHg or less.

When the screw rotation speed is increased for a given amount of extrusion, the polyester surface existing on the screw surface can be forcibly renewed, and the degassing efficiency of water increases accordingly. In other words, it can be said that the deaeration efficiency is better when the screw rotation speed is higher for a certain amount of extrusion. However, the resin temperature rises with an increase in the screw rotation speed, and the intrinsic viscosity decreases from a certain region. For this reason, it is preferable that the extrusion amount and the screw rotation speed at the time of adding the slurry are appropriately selected in order to secure the IV retention.

More specifically, the extrusion rate Q (kg / hr.) Per unit time, the screw rotation speed N (rpm),
The relationship between the cylinder inner diameter D (mm) of the extruder is expressed by the following equation (I), preferably the following equation (II), and more preferably the following equation (II).
It is better to satisfy the expression (III). By satisfying such conditions, even if water is used as the medium of the slurry, it is possible to minimize the IV decrease due to hydrolysis.

[0028]

## EQU1 ## 5.2 × 10 ⁻⁶ × D ^2.8 ≦ Q / N ≦ 15.8 × 10 ⁻⁶ × D ^2.8 (I) 6.0 × 10 ⁻⁶ × D ^2.8 ≦ Q / N ≦ 15.0 × 10 ⁻⁶ × D ^2.8 (II) 6.3 × 10 ⁻⁶ × D ^2.8 ≦ Q / N ≦ 14.7 × 10 ⁻⁶ × D ^2.8 (III)

Under the conditions shown in the following formula (IV), the number of revolutions is too high with respect to the amount of extrusion, so that excessive heat generation due to screw shearing tends to deteriorate the IV retention. Further, under the conditions shown in the following equation (V), the rotational speed is too low with respect to the extrusion amount, so that the degree of renewal of the molten resin surface under reduced pressure is reduced and sufficient deaeration cannot be performed, and the IV retention Tends to worsen.

[0030]

## EQU2 ## 5.2 × 10 ⁻⁶ × D ^2.8 > Q / N (IV) Q / N> 15.8 × 10 ⁻⁶ × D ^2.8 (V)

The intrinsic viscosity of the polyester supplied to the vented twin-screw extruder can be arbitrarily selected, but is preferably 0.40 to 1.10 or less, more preferably 0.50 to 1.10.
1.00. If the intrinsic viscosity of the polyester is less than 0.40, the mechanical strength of the molded product is insufficient, which is not preferable. Conversely, if the intrinsic viscosity of the polyester exceeds 1.10, the IV reduction rate increases, which is not preferable. The reduction in the intrinsic viscosity of the polyester extruded from the vented twin-screw extruder is usually 10% or less, but is preferably 9% or less.
% Or less, more preferably 8% or less.

In the present invention, as described above, an addition nozzle for introducing a slurry is not required except for one raw material supply port which is originally a polymer supply port. The point that mixing of a solid and a liquid (including a slurry) using a vent-type twin-screw extruder without separately providing a liquid addition nozzle is the greatest feature of the present invention. It is very surprising. According to the present invention, the following various effects can be obtained together with the advantage that the strength of the cylinder is not reduced.

(I) The slurry is supplied into the heating cylinder (2) under the atmospheric pressure. As a result, the pressure of the slurry is not required and the aggregation of the particles dispersed in the slurry caused by the pump is prevented. The problem of destruction can be avoided. Further, the problem of clogging of the slurry encountered when using the addition nozzle can be avoided. Also,
The temperature of the slurry can be kept below 100 ° C.

(Ii) Since the temperature of the slurry can be kept lower than the boiling point of the medium, rapid evaporation of the medium does not occur. As a result, since no sudden pressure is generated, it is possible to add a very small amount of the liquid slurry to the polyester in a very quantitative manner.

(Iii) The contact time between the polyester and the slurry is sufficiently ensured, and the effect of kneading and dispersing the particles in the polyester is enhanced, so that the dispersibility of the particles in the polyester is improved.

(Iv) Since the medium of the slurry is gently vaporized without a sudden increase in pressure in the polyester transport section, it is easy to remove the vaporized medium from the polymer and slurry inlet (9). Can be done. As a result, since the medium is substantially completely removed before the plasticization of the polyester, it is possible to avoid a decrease in the intrinsic viscosity of the polyester which has conventionally been inevitably generated when water is used as the medium. The problem of venting at the polymer and slurry inlet (9) can be easily avoided by appropriately and strongly rotating the screw (3).

(V) Since the slurry medium is removed from the polymer and the slurry inlet (9), it is not necessary to use dry polyester. When substantially undried polyester is used, the moisture contained in the undried polyester is removed from the vent hole (6) by the action of reduced pressure. Of course, there is no problem in using the dried polyester, for example, when the water content is 50 pp.
The use of polyester dried to less than m does not degrade the properties of the polyester.

[0038]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples and comparative examples, “%” simply means “% by weight”.

(1) Intrinsic viscosity [η] of polyester (d)
l / g): 100 g of a mixed solvent of phenol / tetrachloroethane: 50/50 (weight ratio) was added to 1 g of the polyester from which other polymer components and particles incompatible with the polyester were removed, and dissolved at 30 ° C. It was measured.

(2) Particle dispersibility: The surface of the polyester was ashed using a plasma reactor ("PR41" manufactured by ALCATEL) under the conditions of an oxygen flow rate of 30 (ml / min.) And an output of 30 W. Scanning electron microscope (SE
M) was evaluated by observing the dispersion state of the particles. The case where coarse aggregated particles were present was evaluated as x, the case where coarse aggregated particles were not present and the dispersion was good was evaluated as ○, and the middle was evaluated as Δ.

(3) Suitability of slurry addition: Evaluation was made according to the following criteria. That is, when the slurry could be added in a predetermined amount, it was evaluated as ○, when the slurry supply port was closed, or when the slurry supply pressure exceeded 5 (kg / cm ² ), and as ×.

Example 1 An intrinsic viscosity of 0.650 (dl / g) and a water content of 0.2%
Of substantially undried polyethylene terephthalate and fine silica (“Sylysia SL32” manufactured by Fuji Silysia)
0 ") was supplied from the same raw material supply port to a vented twin-screw extruder having a cylinder diameter of 44 mm and having a structure shown in FIG. 1 and melt-extruded the polyester composition. The screw rotation speed was 350 (rpm), and the amount of slurry added was 1.5 (kg / hr.). The total output was 50 (kg / hr.). The addition of the slurry was performed extremely quantitatively and stably. The intrinsic viscosity of the obtained polyester composition was 0.627 (dl / g), and the dispersibility of the particles therein was also very good. Table 1 summarizes the results.

Example 2 Example 1 was repeated except that substantially undried polyethylene terephthalate having an intrinsic viscosity of 0.621 was used.
A polyester composition was obtained in the same manner as in Example 1. The addition of the slurry was performed extremely quantitatively and stably, and the intrinsic viscosity of the obtained polyester composition was 0.603 (d
1 / g), and the dispersibility of the particles therein was also very good. Table 1 summarizes the results.

Example 3 The intrinsic viscosity was 0.647 (dl / g) and the water content was 0.2%
The same raw material supply of substantially undried polyethylene terephthalate and a water slurry containing 20% of fine silica (“Sylysia SL320”) to a vented twin-screw extruder having a cylinder diameter of 90 mm and having a structure shown in FIG. The polyester composition was supplied by mouth and melt-extruded. The screw rotation speed is 210 (rpm) and the amount of slurry added is 9
(Kg / hr.). The total output is 400 (kg / h
r. )Met. The addition of the slurry was performed extremely quantitatively and stably. The intrinsic viscosity of the obtained polyester composition was 0.613 (dl / g), and the dispersibility of the particles therein was also very good. Table 1 summarizes the results.

Example 4 A polyester composition was prepared in the same manner as in Example 1 except that a slurry prepared using a medium having a composition ratio of 75% water and 25% methanol was used. Obtained. The addition of the slurry was performed extremely quantitatively and stably, and the intrinsic viscosity of the obtained polyester composition was 0.61.
0 (dl / g), and the dispersibility of the particles therein was also very good. Table 1 summarizes the results.

Comparative Example 1 A polyester composition was obtained in the same manner as in Example 1, except that the vented twin-screw extruder shown in FIG. 2 was used. About 30 minutes after the start of the supply of the slurry, the slurry addition port in the heating cylinder was closed, and the supply of the slurry became impossible. As a precaution, the extruder was stopped and the slurry addition port was examined. As a result, fine silica was condensed and dried at the tip.
Table 2 summarizes the results.

Comparative Example 2 The concentration of the water slurry was 7%, and the amount added was 11 (kg / h).
r. ), And polyethylene terephthalate was melt-extruded in the same manner as in Comparative Example 1. Since the supply amount of the water slurry was large, no blockage occurred in the supply portion of the water slurry, but the heating cylinder temperature was high, and the polyester in the heating cylinder was also 100 ° C. or higher,
At the same time as the addition of the water slurry, the water as the medium boiled violently, and it was difficult to supply the water slurry stably and quantitatively unless the supply pressure of the water slurry was 8 (kg / cm ² ) or more. Table 2 summarizes the results.

Comparative Example 3 The concentration of the water slurry was 10%, and the addition amount was 2 (kg / h).
r. ), Except that polyethylene terephthalate was melt-extruded in the same manner as in Comparative Example 1. About one hour after the supply of the slurry was started, the slurry addition port in the heating cylinder was closed, and the supply of the slurry became impossible. As a result, the extruder was stopped and the slurry addition port was checked.
Fine silica was coagulated and dried at the tip. Table 2 summarizes the results.

[0049]

Table 1 ──────────────────────────────────── Example 1 2 3 4 Intrinsic viscosity IV : Dl / g 0.650 0.621 0.647 0.650 Slurry medium Water Water Water Water / Methanol Slurry concentration: wt% 15 15 20 15 Slurry addition position A A A A Slurry addition amount: Kg / Hr. 1.5 1.5 1.3 1.5 Total extrusion amount: Kg / Hr. 50 50 400 50 IV after extrusion: dl / g 0.627 0.603 0.613 0.610 Particle dispersibility ◎ ◎ ◎ ○ Suitability for slurry addition ◎ ◎ ◎ ○ Overall evaluation ◎ ◎ ◎ ○ ─────────────位置 Slurry addition position A: Same as the polyester supply port.

[0050]

[Table 2] Comparative Example 1 23 Intrinsic viscosity IV: dl / g 0.650 0.650 0.647 Slurry Medium Water Water Water Slurry concentration: wt% 15 7 10 Slurry addition position BB B Slurry addition amount: Kg / Hr.h 1.5 11.0 2.0 Total extrusion amount: Kg / Hr. 50 50 50 IV after extrusion: dl / g-0.541 − Particle dispersibility − × − Suitability for slurry addition × × × Overall evaluation × × × 位置 Slurry addition position B: Different from polyester supply port.

[0051]

According to the present invention described above, there is provided a method for producing a polyester composition containing inorganic particles and / or organic particles using a vented twin-screw extruder, wherein the particles are added with high quantitativeness. And the decrease in the intrinsic viscosity of the polyester is extremely small,
A method for producing a polyester composition having excellent moldability and quality of a molded article is provided, and the industrial value of the present invention is remarkable.

[Brief description of the drawings]

FIG. 1 is an explanatory side view of an example of a vented twin-screw extruder used in the production method of the present invention.

FIG. 2 is an explanatory side view of a vent type twin screw extruder used in a conventionally known manufacturing method.

[Explanation of symbols]

 1: Bent type twin screw extruder (molding machine) 2: Heating cylinder 3: Screw 4: Extrusion port 5: Polymer inlet 6: Vent hole 6 ': Vent hole 7: Slurry addition port 8: Reverse screw 8': Reverse Screw 9: Polymer and slurry inlet M: Screw drive

Claims (3)

[Claims] 1. A method for producing a polyester composition containing inorganic particles and / or organic particles, wherein a polyester and a slurry of inorganic particles and / or organic particles are supplied from the same raw material supply port to a vented twin-screw extruder. A method for producing a polyester composition, comprising: 2. The method according to claim 1, wherein a slurry of inorganic particles and / or organic particles substantially using water as a medium is used. 3. The method according to claim 1, wherein a substantially undried polyester is used.