JPS6148405B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing thermoplastic polymer moldings, and more particularly to a method for economically producing thermoplastic polymer moldings in which additives are uniformly mixed. Thermoplastic polymers, such as polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as 6-nylon and 66-nylon, and polyolefins such as polyethylene and polypropylene, have many excellent properties. Because of this, it is widely used in fibers, films, and other molded products, which are generally melt-molded after drying. However, in order to further expand these uses, attempts are being made to mix various additives with the aim of improving their properties or eliminating their drawbacks. Conventionally, in order to manufacture polymer molded articles mixed with additives, especially solid-phase additives, there have been two methods: adding and mixing the additives during polymer synthesis, and mixing polymer chips and additives using a mixer. The most commonly used method is to dry and then mold the material. However, in the former method, the synthesis process becomes complicated,
There are disadvantages such as contaminating the synthesis equipment and furthermore, depending on the type of additive, it may decompose and deteriorate under the synthesis conditions, and the latter method requires an extra mixer.
Furthermore, when applied to continuous drying and melt molding, there are drawbacks such as difficulty in uniformly mixing additives. In an attempt to overcome the above-mentioned drawbacks, the present inventor attempted to feed polymer chips and additives in fixed amounts separately into a continuously operating dryer and then mix the two in the dryer. However, in this method, the additives in the molded product obtained are not mixed uniformly, and only a non-uniform product is obtained. Furthermore, as a result of extensive research into this method, we found that if a pressure release port is provided near the outlet of the additive meter and the polymer chips and additives are combined in the pipe in front of the dryer, the additives can be removed. The present invention was developed based on the knowledge that a uniformly mixed molded product can be obtained. That is, the present invention involves continuously and separately weighing thermoplastic polymer chips and solid-phase additives, supplying them to a dryer to dry them, and then melt-molding them to produce a thermoplastic polymer molded product. A thermoplastic polymer molded article, characterized in that a pressure release port is provided between at least an additive meter and a dryer, and the thermoplastic polymer chips and additives are combined in a pipe in front of the dryer. This is a manufacturing method. The present invention will be explained using figures. The figure is a simplified diagram showing an embodiment of the present invention, in which 1 is an additive hopper, 2 is an additive meter, 3 is a pressure outlet,
4 is a rotary feeder, 5 is an additive supply pipe, 6
7 is a hopper for polymer chips, 7 is a rotary feeder for weighing polymer chips, 8 is a polymer chip supply pipe, 9 is an additive supply pipe 5 and a polymer chip supply pipe 8
10 is a dryer. It is necessary to provide a pressure release port 3 between the additive measuring device 2 and the dryer 10. By doing so, it is possible to accurately and smoothly measure and flow the additive. The pressure release port 3 may be located anywhere between the additive measuring device 2 and the dryer 10, but it should be located as far away from the dryer 10 as possible in order to prevent loss of hot air inside the dryer. If so, it is preferable to install it near the outlet of the meter 2, and it is also preferable to install a rotary feeder between the pressure release port 3 and the dryer 10 as shown in the figure, since hot air loss inside the dryer can be further prevented. . Further, a pressure release port may be provided between the polymer chip measuring device and the dryer. In addition, the polymer chips and additives are dried in a dryer.
They should be merged in the piping before entering.
9 in the figure is the meeting point of both. This merging point does not need to be particularly limited and may be near the dryer inlet, but it is usually preferably at least 0.3 m away from the dryer. In order to merge the two in a pipe, the additive may be supplied during the flow of polymer chips, but in particular, as shown in the figure, a straight pipe section extending in a straight line is provided in the additive supply pipe 5. If a polymer chip supply pipe is connected to this straight pipe as a branch pipe branching from here and the polymer chips are fed into the flow of the additive, the distribution of the additive in the resulting molded product will be improved. This is preferable because it becomes uniform. Note that if the polymer chips and additives are fed separately to the dryer, the distribution of the additives in the resulting molded product will be uneven. The dryer used here does not need to be of a special type as long as it is a continuous type, and for example, a rotary dryer, a fluidized bed dryer, an agitation dryer, etc. are preferably used. Further, there is no need to adopt a special method for melt molding performed after drying, and any method such as an extruder method or a melt lattice method can be employed. The thermoplastic polymer referred to in the present invention may be any thermoplastic polymer that can be melt-molded, particularly polyester such as polyethylene terephthalate and polybutylene terephthalate, 6-nylon, 66
- Polyamides such as nylon, polyolefins such as polyethylene and polypropylene, etc. are preferred. Further, the shape thereof may be any shape other than powder, such as granules, cylinders, prisms, dice, flat plates, and flakes, and in the present invention, these are abbreviated as chips. Further, the additive referred to in the present invention may be any additive as long as it maintains a solid phase state under drying conditions of the above polymer, such as an antistatic agent, a flame retardant, a coloring agent, a fluorescent whitening agent, etc. Examples include lubricants, stabilizers, dyeing agents, etc. Further, the shape thereof may be arbitrary such as powder or granule, and it is particularly preferable to have the same or similar shape to the above-mentioned polymer chips to be mixed. In particular, if the above-mentioned polymer is used in the form of chips containing a high concentration of additives, so-called master chips, it is possible to sufficiently prevent the classification of polymer chips and additives that is likely to occur in a dryer. This is preferable because it can be done. The ratio of the additive to the polymer chip can be varied over a very wide range, for example from a fraction of a fraction to a fraction of a hundredth, without any problem. According to the present invention, it is possible to extremely economically produce molded articles in which additives are uniformly mixed continuously over a long period of time without using a special mixer or without contaminating the polymer synthesis equipment. I can do it. The present invention will be further explained below with reference to Examples.
Incidentally, the mixed mottling of the additives was measured by knitting and dyeing the obtained filament and measuring the degree of the dyeing mottling. Staining spots are performed using a five-step method,
Grade 5 is the best, grade 1 is the worst, and grade 3 is the best.
A grade above grade was considered a passing grade. Examples 1 to 3 and Comparative Examples 1 and 2 The apparatus shown in the figure was used, and Acrison 101-BC manufactured by Toho Elesineering Co., Ltd. was used as an additive measuring device.
Using a type continuous meter, the straight part of the additive supply pipe was made to have an inner diameter of 80 mm, the polymer chip supply pipe was made into a branch pipe with an inner diameter of 100 mm, and the distance from the confluence of both supply pipes to the dryer was 10 m. A rotary hot air dryer was used as the dryer. Polyethylene terephthalate chips (chip shape: 4 x 4 x 2 (mm) flat plate) with an intrinsic viscosity (25°C, in orthochlorophenol solvent) of 0.60 are fed from a polymer chip hopper 6 to a rotary feeder 7 at a rate of 335 kg per hour. Continuously metered and supplied in proportions,
At the same time, from the additive hopper 1, using the measuring device 2, master chips prepared by mixing 5% by weight of polyoxyethylene glycol with an average molecular weight of 20,000 with polyethylene terephthalate having an intrinsic viscosity of 0.60 in various shapes shown in Table 1 were added at a rate of 110 kg per hour. Continuously metered in proportions. The temperature inside the dryer was maintained at 140°C, and the residence time of the chips in the dryer was 3 hours.
After drying, the mixed chips are temporarily stored in a tank installed just before the spinning machine, then supplied to the spinning machine, and the melting temperature is
Melt and discharge with an extruder at 280℃,
It was wound at a speed of 1100 m/min to obtain an undrawn yarn with a single yarn fineness of 7 denier. This undrawn yarn was drawn three times at 75°C and heat-set at 120°C. The staining spots indicating additive mixing spots are shown in Table 1. For comparison, the same procedure as in the above Example was carried out except that the pressure relief port 3 shown in the figure was closed to eliminate the pressure relief effect, and the results are shown in Table 1 as Comparative Example 1. Furthermore, for comparison, the same procedure as in the above example was carried out except that the polyethylene terephthalate chips supply pipe was directly connected to the dryer and the polyethylene terephthalate chips and master chips were separately supplied to the dryer, and the results were used as Comparative Example 2. Shown in the table.

[Table] Example 4 Except that the polyethylene terephthalate chip supply pipe and master chip supply pipe in Example 1 were installed in reverse, that is, the master chip supply pipe was installed as a branch pipe on the straight pipe part of the polyethylene terephthalate chip supply pipe. When the same procedure as in Example 1 was carried out, the staining spots were grade 3 to 3.5. Example 5 Using the same equipment as in Example 1, 6-nylon chips (chip shape: 2mmφ×2mm
(cylindrical shape) at a rate of 360 kg per hour, and at the same time, from the additive hopper 1, the average molecular weight
Master chips containing 7% by weight of 10,000 polyoxyethylene glycol were continuously metered in at a rate of 90 kg/hour. Nitrogen was used as the drying medium in the dryer, maintained at 130°C, and the residence time of the chips in the dryer was 4 hours. After drying, the chips are isolated from air and continuously fed into an extruder, extruded into a film at a melting temperature of 260°C and a discharge speed of 30 m/min, and stretched 4 times in the length direction and 2 times in the width direction. A biaxially stretched film with a thickness of 20 μm was obtained, and this film was dyed, and the dyed spots were 5
When expressed in stages and used as a scale for polyoxyethylene glycol mixed spots, the staining spots were grade 3.5 to grade 4.

[Brief explanation of the drawing]

The figure is a simplified diagram showing an example of an embodiment of the present invention. In the figure, 2 is a measuring device for additives, 3 is a pressure outlet, 7 is a measuring device for polymer chips, 9 is a confluence point of additives and polymer chips, and 10 is a dryer.

Claims (1)

[Claims] 1. Thermoplastic polymer chips and solid phase additives are continuously and separately weighed, fed to a dryer and dried,
Next, when producing a thermoplastic polymer molded article by melt molding, a pressure release port is provided at least between the additive meter and the dryer, and the thermoplastic polymer chips and additives are removed before the dryer. A method for producing a thermoplastic polymer molded article, characterized by merging it in a pipe. 2. The joining of the thermoplastic polymer chips and the additive is carried out by feeding the thermoplastic polymer chips into the flow of the additive through a thermoplastic polymer supply branch pipe connected to the straight pipe section of the additive supply pipe. A method for producing a thermoplastic polymer molded article according to claim 1. 3. The method for producing a thermoplastic polymer molded article according to claim 1 or 2, wherein the additive has the same or similar shape and size as the thermoplastic polymer chips.