JPH11226947A - Polytrimethylene terephthalate chip with extreme ease of handling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyrimethylene terephthalate chip which is almost free from the generation of a powder polymer which could be causes for the faulty operation of an air blower, an exhauster and their filters or the fluctuation of pressure in a screw during melting/extrusion when cutting a molten polymer or in a pneumatic line used for conveying the chips. SOLUTION: This chip passes through a 10-mesh filter and a powder sticking to the surface of the chip which is not passable through a 300-mesh filter is of the size of 1,000 mg/g or less. The method for manufacturing this chip is to set the melt-extruded polymer so that the crystallinity index is 25% or less and cut the set polymer into chips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to polytrimethylene terephthalate, which has a low generation of powdery polymer which causes a malfunction of an air blower and a blower for transporting chips, and a fluctuation of screw pressure at the time of extrusion. The present invention relates to a chip and a method for manufacturing the chip.

[0002]

2. Description of the Related Art In recent years, polytrimethylene terephthalate has been used for carpet applications due to its soft hand and easy dyeability.
Or, it is beginning to attract attention for use in clothing. Usually, a polyester polymer such as polytrimethylene terephthalate is melt-extruded into a rope after melt polycondensation, cooled in water, cut into a suitable size, and formed into chips. As a result of examining the chip, it was found that a chip having low impact resistance was produced depending on the cooling conditions of the melt-extruded polymer. In particular, it has been found that the tendency of polytrimethylene terephthalate is more remarkable than other polyester polymers such as polyethylene terephthalate and polybutylene terephthalate.

[0003] Chips having low impact resistance tend to become powdery due to contact with metal or between chips in a pneumatic transporter (Newmar Line) used for transporting chips, and clogging of blowers and exhaust fans. It is easy to cause malfunction. In addition, if a powder removal filter is inserted as a measure against clogging, loss of polymer occurs, and operations such as filter replacement are added, resulting in an increase in cost.
Furthermore, if the powdery polymer is present in a form attached to the chips, the melt state in the melt extruder fluctuates, and quantitative melt extrusion cannot be performed, so that screw pressure fluctuations occur during extrusion. When such a phenomenon occurs, it tends to cause yarn spots during spinning.

It is considered that polytrimethylene terephthalate is more likely to cause the above-mentioned phenomena than other polyester polymers because it has a high crystallization speed and is easy to crystallize even at a low temperature. For this reason, in the same chip manufacturing method as that of the conventionally performed PET, a powdery substance is easily generated. Various methods have been proposed for producing a polytrimethylene terephthalate polymer (Japanese Patent Application Laid-Open (JP-A) Nos. 51-140992 and 5-26).
2862, JP-A-8-31177, etc.).
However, there is no disclosure of a specific method of chip formation. Further, as for the method for producing a polyethylene terephthalate chip, as described in JP-A-5-70567, there is a description about the intrinsic viscosity difference and the density difference between the inner and outer layers. There is hardly any description about such things.

[0005]

SUMMARY OF THE INVENTION The present invention improves on the above-mentioned drawbacks of the conventional polyester chips and reduces the filter clogging, polymer loss and screw pressure of the Newmar line blower and exhaust fan used for chip transportation. The present invention relates to a polytrimethylene terephthalate chip which is suitable for melt molding typified by spinning and has excellent handleability, in which a problem such as fluctuation is unlikely to occur, and a method for producing the same.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned drawbacks. As a result, a polymer having a specific structure is formed into chips, and the polymer is used for transporting chips. Polytrimethylene terephthalate suitable for melt molding, with less screw pressure fluctuations in the melt extruder during spinning, less occurrence of problems such as filter clogging and polymer loss. A chip and a method for manufacturing the same have been provided.

[0007] That is, the first aspect of the present invention is characterized in that a powdery polymer of 1000 mg / (g chip) or less that passes through a 10-mesh filter but does not pass through a 300-mesh filter adheres to the chip surface. It is a trimethylene terephthalate chip. The second aspect of the present invention is a method for producing polytrimethylene terephthalate chips, comprising solidifying a melt-extruded polymer so that the crystallinity thereof is 25% or less, cutting the polymer into chips, and cutting the chips. .

The polytrimethylene terephthalate of the present invention is a polyester polymer containing terephthalic acid as an acid component and containing at least 80 mol% of trimethylene glycol as a glycol component. In the present invention, the trimethylene glycol is selected from 1,3-propanediol, 1,2-propanediol, 1,1-propanediol, 2,2-propanediol, and a mixture thereof. From the perspective of 1,
3-propanediol is particularly preferred.

In the polytrimethylene terephthalate used in the present invention, if necessary, isophthalic acid, succinic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, etc. may be used as long as the effects of the present invention are not impaired. A glycol component such as ethylene glycol, 1,4-butanediol, 1,6-hexanediol, or polyoxyalkylene glycol may be copolymerized as the glycol component. If necessary, various additives such as a matting agent, a heat stabilizer, a flame retardant, an antistatic agent and an antifoaming agent may be copolymerized or mixed.

The chip of the present invention contains 1000 mg / powder polymer which passes through a 10-mesh filter attached to the chip surface and does not pass through a 300-mesh filter.
(G chip) must be less than or equal to. If the amount of the powdered polymer exceeding 1,000 mg / (g chip) that does not pass through the filter of 300 mesh exceeds 1000 mg / (g chip), the filter of the blower and the exhauster of the Newmar line may be easily clogged, and the melt extruder may be used for spinning. Fluctuations in screw pressure occur in the inside, and thread spots are likely to occur. The smaller the amount of powdered polymer, the better, but practically 10
It is preferably at most 0 mg / (g chip), more preferably at most 30 mg / (g chip).

In addition, the chips of the present invention require that the melt-extruded polymer be solidified so as to have a crystallinity of 25% or less, and cut into chips. If the crystallinity exceeds 25%, the impact resistance of the chip will be extremely deteriorated,
The metal or the chip is easily broken by contact with each other, and a powdery polymer is easily generated. In the present invention, the intrinsic viscosity [η] of the polytrimethylene terephthalate polymer is 0.1.
It is preferably in the range of 4 to 1.5. If the intrinsic viscosity exceeds 1.5, the melt viscosity becomes too high, and it becomes difficult to perform melt molding. If it is less than 0.4, the mechanical properties of the molded product will not be sufficient. The polymer used in the present invention can be polymerized by a known polyester polymerization method. For example, a method of directly esterifying an acid and a glycol followed by polycondensation in the presence of a suitable catalyst, a transesterification reaction of a lower alkyl ester of an acid and a glycol in the presence of a suitable catalyst, followed by melt polycondensation. Method and the like.

The polymer thus melt-polymerized is melt-extruded, cooled with an appropriate solvent, and cut into chips. In the present invention, when forming chips, the molten polymer is reduced to 0 to control the crystallinity of the chips to 25% or less.
It is necessary to solidify in a solvent whose temperature has been adjusted to 40 ° C. or lower. Further, it is necessary to suppress the frictional heat generated during cutting and keep the temperature of the chip at 60 ° C. or less. If the solvent temperature exceeds 40 ° C., the solidification temperature of the polymer exceeds 60 ° C., the crystallinity of the polytrimethylene terephthalate polymer exceeds 25%, and a brittle chip having low impact resistance is produced. On the other hand, if the frictional heating temperature at the time of cutting exceeds 60 ° C., a brittle layer with low impact resistance with crystallization progressed is formed on the chip surface.

Since water is usually used as a cooling solvent,
It is difficult to keep the temperature below ° C. The temperature at the time of cutting is preferably in the range of 5 to 35C, more preferably 10 to 30C. The cooling rate of the extruded polymer is 100 ° C. /
Desirably, it is at least minutes. If the cooling rate is less than 100 ° C./min, it takes a long time to cool, and crystallization is likely to occur during cooling, resulting in a brittle chip having low impact resistance. The faster the cooling rate, the better, but practically 300 ° C /
Min or more, more preferably 500 ° C./min or more. Of course, in order to rapidly cool and solidify the polymer, alcohol, glycol, etc. other than water whose temperature has been adjusted to 0 to 40 ° C. may be used as a solvent. Further, in order to suppress heat generation during cutting, it is necessary to cool during cutting, and it is preferable to cut in the above-mentioned cooling solvent or to cut while applying a cooling solvent. Of course, a cooled blade may be used for cutting.

It is necessary to adjust the thickness of the extruded polymer so that the weight of one chip is 1 to 1000 mg or less. If it is 1 mg or less, it is possible to rapidly cool the polymer, but since the chip is too small, it adheres to a wall or the like due to static electricity during transportation or storage, so that handling becomes difficult. If it is 1000 mg or more, it becomes difficult to cool the polymer from the outer layer to the inner layer at a cooling rate of 100 ° C./min or more as described above, and the inner layer portion is crystallized, resulting in a chip having low impact resistance. It becomes easy to form a polymer. In addition, it is difficult to carry the compressed air, which is usually used, because the chips are too large, and it is also difficult to melt the material with an extruder during melt molding. The size of the chip is preferably 5 to 500 mg, more preferably 10 to 200 mg.
mg range.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples and the like, but the present invention is not limited to the examples and the like. The main measured values in the examples were measured by the following methods. (1) Amount of powdery polymer adhering to chip surface The amount of the powdery polymer adhering to the chip surface was measured according to the following procedure. 1. Put 500 g of chips in a beaker containing water. Stir for 2.5 minutes to wash off powdery polymer adhering to the surface. 3.2 is filtered through a 500 mesh filter and washed repeatedly with water so that no powdery polymer remains on the chips on the filter. 4.3 Filter the filtrate again through a 300 mesh filter. The filtration residue of 5.4 is dried under reduced pressure at 80 ° C., and the weight is measured.

(2) Measurement of Crystallinity of Chip The crystallinity of the chip was measured under the following conditions. Measuring device: Rotaflex RU-200 Rigaku Corp. Sample form: Tip X-ray type: CuKα ray X-ray intensity: 40 kv, 120 mA Slit interval: DS = 0.6, RS = 0.3, SS
= 1 Calculation of crystallinity: peak separation method

(3) Evaluation of yarn spots As an accelerated evaluation method, eight fibers were spun under the following conditions using an eight-end spinning machine, and the yarn spots were evaluated by U% of the yarn. USTER TESTER3 manufactured by Zellbeger Worcester was used for the measurement of U%. Extrusion temperature: 270 ° C. Spinning tip: 36 holes having a diameter of 0.23 mmφ arranged in a single line Discharge rate: 23 g / min Winding speed: 5000 m / min

(4) Intrinsic viscosity [η] Intrinsic viscosity [η] is a value obtained based on the following defining equation. [Η] = lim 1 / [C × (ηr-1)] C → 0 ηr in the definition formula is the viscosity at 35 ° C. of a diluted solution of polytrimethylene terephthalate dissolved in o-chlorophenol having a purity of 98% or more. Divided by the viscosity of the solvent itself measured at the same temperature, and is defined as a relative viscosity. C is the solute weight value in grams in 100 ml of the solution.

[0019]

Example 1 1,3-Propanediol and dimethyl terephthalate were polymerized by a conventional method, and the intrinsic viscosity [η] of 0.1.
As a result, polytrimethylene terephthalate polymer No. 7 was obtained.
The obtained polymer was extruded into water whose temperature was adjusted to 10 ° C. from a discharge hole having a diameter of 5 mm, and cut in water. After that, chips exceeding 200 mg were removed by a sorter using a wire mesh, and an average size of 50 mg was obtained. A polytrimethylene terephthalate chip was obtained. At this time, the polymer temperature at the time of cutting was 30 ° C., and the cooling rate was 720 ° C./min. Further, the polymer temperature did not exceed 30 ° C. due to the cutting. The chips collected under the above conditions were transported by a pneumatic line, and then the amount of the powdery polymer adhering to the chip surface was measured. 89 mg of powdery polymer attached to the chip surface
(G chip). The crystallinity of the chip before the transportation of the pneumatic line was 7%. When this polymer was evaluated for spinning, the screw pressure during melt extrusion was stable, and the U% of this yarn was very good at 1.5%.

[0020]

Examples 2 and 3, Comparative Examples 1 and 2 Polymer cooling temperature,
A chip was manufactured in the same manner as in Example 1 except that the cooling rate and the size of the polymer were changed as shown in Table 1. Under the chip manufacturing conditions in the range of the present invention, good chips were obtained, there was no fluctuation in screw pressure during melt extrusion, and the spinnability was good. On the other hand, under chip production conditions outside the range of the present invention, only brittle chips having poor impact resistance were obtained, and there was a large fluctuation in screw pressure during melt extrusion, which caused a problem in spinnability. The conditions and results are shown in Table 1.

[0021]

[Table 1]

[0022]

The polytrimethylene terephthalate chip of the present invention improves the disadvantages of the conventional polyester chip, hardly causes problems such as clogging of the filter of the Newmar line used for transporting the chip, and has excellent handleability. Suitable for melt molding such as spinning.

Claims (2)

[Claims] (1) passing through a 10-mesh filter;
Powdery polymer that does not pass through a 00 mesh filter 1
A polytrimethylene terephthalate chip, wherein less than 000 mg / (g chip) adheres to the chip surface. 2. A melt-extruded polymer having a crystallinity of 2
A method for producing polytrimethylene terephthalate chips, wherein the chips are solidified to 5% or less and cut into chips.