JP6907725B2 - Method for producing thermoplastic resin composition - Google Patents

Description

The present invention relates to a method for producing a thermoplastic resin composition.

Thermoplastic resins can be imparted with various properties by adding additives, and are used as useful materials in various fields. On the other hand, in recent years, from the viewpoint of environmental protection, reduction of waste has been required, and as one means for that purpose, used products made of thermoplastic resin (hereinafter, also referred to as "waste materials") are collected and used. Is known to be reused as a raw material for new products made of thermoplastic resins.

Waste materials are generally collected for each type of thermoplastic resin. The recovered individual waste materials have unique physical properties according to the original use. Therefore, the waste material generally has the same type of resin but different physical characteristics. Therefore, when the waste material is reused as a raw material for a new product made of thermoplastic resin, it is necessary to suppress the influence of variation in physical properties due to the waste material.

As a technique for suppressing variation in physical properties of waste materials, a technique of using only waste materials having similar physical properties is known (see, for example, Patent Document 1). In this technique, a raw material for a thermoplastic resin having desired physical properties is obtained by not using waste materials having significantly different physical characteristics.

Further, there is also known a technique of suppressing variation in physical properties of waste materials by mixing a large amount of waste materials in advance.

Further, when a waste material is used, a technique for adjusting the staying time in the melt kneader, the temperature of the waste material, the temperature of the cylinder, and the supply amount of the waste material to the melt kneader is also known (see, for example, Patent Document 2). .. In this technique, a raw material for a thermoplastic resin having desired physical properties is obtained by setting conditions according to the waste material.

Japanese Unexamined Patent Publication No. 2005-120186 Japanese Unexamined Patent Publication No. 10-151623

However, if the technique described in Patent Document 1 is adopted, waste material that cannot be used as a material to be put into the melt kneader is generated, so that the production cost may increase. Further, when the technique described in Patent Document 2 is adopted, it may not be possible to cope with the time-dependent variation of the waste material charged into the melt-kneader, and the shape of the resin strand discharged from the melt-kneader may not be stably maintained. .. As described above, when an attempt is made to obtain a thermoplastic resin composition using a waste material, the shape of the resin strand is not stable, and the resin strand may be cut in some cases. In this case, it is necessary to suspend the production of the thermoplastic resin composition for restoration, which may reduce the productivity.

In the present invention, a resin strand discharged from a melt-kneader is being manufactured by using a raw material made of a thermoplastic resin having a variation in physical properties and sufficiently reducing the variation in physical properties of a product due to the variation in physical properties of the raw material. An object of the present invention is to provide a method for continuously producing a thermoplastic resin composition while suppressing cutting.

As one aspect for solving the above-mentioned problems, the present invention comprises melt-kneading a recovery material made of a thermoplastic resin with a melt-kneader, and then winding the resin strands discharged from the melt-kneader with a pelletizer. , A method for producing a composition made of a regenerated thermoplastic resin, wherein the step of measuring the melt viscosity of the recovered material, the step of measuring the melt tension of the recovered material, and the step of melting and kneading the recovered material. The shape of the resin strand including the step of melt-kneading with a machine, the thickness of the resin strand after being discharged from the melt-kneader, and the trajectory of the resin strand after being discharged from the melt-kneader is measured. A step, a step of obtaining a thermoplastic resin composition by winding the resin strand with the pelletizer while cooling the resin strand, a measurement result of the melt viscosity, a measurement result of the melt tension, and a shape of the resin strand. Based on the measurement result, the step of adjusting the conditions of the melt kneader and the conditions of the pelletizer so as to cancel the fluctuation of the shape of the resin strand due to the variation in the physical properties of the recovered material is included.

According to the present invention, a thermoplastic resin composition can be continuously produced.

FIG. 1 is a diagram schematically showing a method for producing a thermoplastic resin composition. FIG. 2 is a schematic view for explaining a process of measuring the shape of the resin strand.

Hereinafter, an embodiment of the present invention will be described.

[Manufacturing method of thermoplastic resin composition]
The method for producing a thermoplastic resin composition according to one embodiment of the present embodiment is a method for producing a recycled thermoplastic resin composition from a recovered material containing a thermoplastic resin. The method for producing a thermoplastic resin composition includes a first step, a second step, a third step using a melt-kneader, a fourth step, a fifth step, and a sixth step.

The first step is a step of measuring the melt viscosity of the recovered material.

The recovered material contains a thermoplastic resin. Examples of thermoplastic resins include polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS resin), polycarbonate (PC), polyethylene terephthalate (PET) and polybutylene. Terephthalate (PBT) is included. The thermoplastic resin may be contained alone or may contain two or more kinds.

Thermoplastic resins are used thermoplastic resin products recovered from the market or waste materials that are crushed products thereof, and unused thermoplastic resin products that are recovered before they are put on the market or unused products that are crushed products thereof. including. When used as a thermoplastic resin, waste materials and unused products are generally classified as crushed products according to the type of resin, or used as a mixed product of the classified products.

The recovered material may be composed only of the thermoplastic resin, or may further contain other additives. Examples of additives include colorants, flame retardants, lubricants, compatibilizers, antioxidants and UV absorbers. The additive may be used alone or in combination of two or more.

Examples of colorants include resin colorants such as inorganic pigments and organic pigments. Examples of flame retardants include phosphorus compounds such as phosphoric acid esters and bromo compounds. Examples of lubricants include metal salts of higher fatty acids and higher fatty acid amides. Examples of compatibilizers include random copolymer-based, graft-copolymer-based, and block-polymer-based compatibilizers. Examples of antioxidants include hindered phenol-based, sulfur-containing organic compound-based, and phosphorus-containing organic compound-based antioxidants. Examples of UV absorbers include benzotriazole-based, benzophenone-based, and salicylate-based UV absorbers.

The content of the additive is preferably 0.3% by mass or more, and more preferably 0.5% by mass or more, from the viewpoint of exerting the effect of adding the additive. The content of the additive is preferably 20% by mass or less, more preferably 15% by mass or less, from the viewpoint of not affecting the melt-kneading step.

The measurement of the melt viscosity of the recovered material is performed before the recovered material is put into the melt kneader. In the present embodiment, since the recovered material is continuously charged into the inlet of the melt kneader, the melt viscosity may be measured at arbitrary intervals.

More specifically, a part of the recovered material may be sampled and the melt viscosity may be measured while the recovered material is being conveyed to the inlet. The measurement of the melt viscosity may be completed before the recovered material is charged into the inlet. If the measurement result of the melt viscosity of the recovered material is not within the specified value, the conditions of the melt kneader and the conditions of the pelletizer are adjusted in the adjusting step.

Further, as an index of the melt viscosity, for example, melt flow rate (MFR) may be used. The MFR value of the recovered material can be measured by the method specified in JIS K7210. Further, the MFR value can be measured by a known (commercially available) measuring device. Examples of measuring devices include a melt indexer (MFR measuring device). The measured value of the MFR value may be a value representing the MFR value of the recovered material, and may be, for example, an average value of a plurality of measured values, a maximum value, or a minimum value. It may be an intermediate value between these.

The second step is a step of measuring the melt tension of the recovered material.

The measurement of the melt tension is performed before the recovered material is put into the melt kneader, similar to the measurement of the melt viscosity. In the present embodiment, since the recovered material is continuously charged into the melt kneader, the melt tension may be measured at arbitrary intervals.

More specifically, a part of the recovered material may be sampled and the melt tension of the recovered material may be measured while the recovered material is being conveyed to the input port. The measurement time of the melt tension may be completed after sampling and before the recovered material is charged into the charging port. If the measurement result of the measurement result of the melt tension in the recovered material is not within the specified value, the conditions of the melt kneader and the conditions of the pelletizer are adjusted in the adjustment step.

The melt tension can be measured with a known (commercially available) measuring device. Examples of measuring devices include capillary rheometers. The measured value of the melt tension may be a value representing the melt tension of the recovered material, and may be, for example, an average value of a plurality of measured values, a maximum value, or a minimum value. It may be an intermediate value between these.

Further, it is preferable that the measurement of the melt viscosity of the recovered material and the measurement of the melt tension of the recovered material are performed on the recovered material sampled at the same time.

The third step is a step of melt-kneading the recovered material with a melt-kneader. A known (commercially available) machine can be used as the melt-kneader for melt-kneading the recovered material. For example, the melt-kneading machine has a charging port for charging the recovered material, a cylinder for melt-kneading the charged recovered material, and a die for discharging the melt-kneaded recovered material to the outside.

The temperature of the cylinder during melt-kneading can be appropriately selected according to the type of recovered material. For example, when the thermoplastic resin contained in the recovered material is a PC, the temperature of the cylinder is in the range of 160 to 240 ° C. Further, for example, when the thermoplastic resin contained in the recovered material is ABS resin, the temperature of the cylinder is in the range of 140 to 220 ° C.

Further, the temperature of the die of the melt kneader can be appropriately selected according to the type of the recovered material. For example, when the thermoplastic resin contained in the recovered material is a PC, the temperature of the die is in the range of 140 to 240 ° C. Further, for example, when the thermoplastic resin contained in the recovered material is ABS resin, the temperature of the die is in the range of 120 to 220 ° C.

The recovered material melt-kneaded by the melt-kneader is discharged from the die to the outside of the melt-kneader as resin strands.

The fourth step is a step of measuring the shape of the resin strand discharged from the melt kneader. Here, the "shape of the resin strand" is information that can specify the shape of the resin strand. In the present embodiment, the shape of the resin strand includes the thickness of the resin strand after being discharged from the melt kneader and the trajectory (tension) of the resin strand after being discharged from the die of the melt kneader. ..

The thickness of the resin strand can be measured with a known (commercially available) measuring device. Examples of measuring devices include non-contact sensors and devices that combine a CCD camera and an image analysis device.

The thickness of the resin strand can be measured at any position after the resin strand is ejected from the die. In the present embodiment, the position where the thickness of the resin strand is measured is the position immediately after being discharged from the melt kneader (the position 10 mm away from the melt kneader).

The specified value of the thickness of the resin strand can be appropriately set according to the melt kneader to be used, as long as the resin strand is not cut before being wound by the pelletizer after being discharged from the melt kneader. For example, the specified value of the thickness (diameter) of the resin strand is in the range of 2 mm or more and 3 mm or less. That is, in the present embodiment, when the diameter of the resin strand is less than 2 mm or more than 3 mm, the conditions of the melt kneader and the conditions of the pelletizer are adjusted in the adjusting step.

The orbit of the resin strand can be measured with a known (commercially available) measuring device. Examples of measuring devices include devices that combine a non-contact sensor, a CCD camera and an image analysis device. Further, the trajectory of the resin strand can be measured at an arbitrary position after being discharged as the resin strand. For example, the orbit of the resin strand may be examined to see if the resin strand passes through a predetermined position. For example, the position for measuring the trajectory of the resin strand is a position 100 mm away from the die of the melt kneader. Further, the trajectory of the resin strand can be appropriately set as long as the resin strand can be appropriately wound by the pelletizer. For example, the specified value of the orbit of the resin strand means that the deviation from the reference line connected by a straight line is within 20 mm. If the orbit of the resin strand is not within the specified value, the conditions of the melt kneader and the conditions of the pelletizer are adjusted in the adjustment step.

The fifth step is a step of winding the resin strands with a pelletizer arranged downstream of the resin strands while cooling the resin strands discharged from the die of the melt kneader.

The method for cooling the resin strand and the cooling temperature can be appropriately set. The method for cooling the resin strand may be water cooling or air cooling. In the present embodiment, the method for cooling the resin strand is water cooling. Further, in the present embodiment, the cooling temperature of the resin strand is 30 ° C.

The cooled resin strand is wound up with a pelletizer. The winding speed of the resin strand by the pelletizer can be appropriately set according to the discharge speed of the resin strand by the melt kneader, the thickness of the resin strand, and the trajectory of the resin strand. The winding speed of the resin strand by the pelletizer is about 5 to 100 m / min.

In the sixth step, each manufacturing condition is adjusted so that the resin strand is not cut. In the sixth step, based on the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand, the melt is performed so as to cancel the fluctuation of the shape of the resin strand due to the variation in the physical properties of the recovered material. This is a step of adjusting the conditions of the kneader and the conditions of the pelletizer.

The conditions of the melt-kneader can be appropriately selected as long as the variation in the shape of the resin strand due to the variation in the physical properties of the recovered material can be canceled out. Examples of melt kneader conditions include the temperature of the melt kneader cylinder and the temperature of the melt kneader die. Further, the conditions of the pelletizer can be appropriately selected as long as the variation in the shape of the resin strand due to the variation in the physical properties of the recovered material can be canceled out. Examples of pelletizer conditions include the winding speed of the resin strands by the pelletizer.

For example, by adjusting the conditions of the melt kneader and the pelletizer based on the measured values of the melt viscosity and the measured value of the melt tension of the recovered material, a large variation in the physical properties of the thermoplastic resin composition due to the variation in the physical properties of the recovered material can be made in advance. Suppress (feed forward control). In addition, by adjusting the conditions of the melt-kneader and the pelletizer based on the measured values of the shape of the resin strand, it is possible to suppress small variations in the physical properties of the thermoplastic resin composition due to variations in the physical properties of the recovered material (feedback control). ..

First, the cause of cutting the resin strand due to the change in the shape of the resin strand during the manufacturing process will be described. In the present embodiment, as the material of the thermoplastic resin composition, a recovered material including a waste material and an unused product is used. The recovered material containing the waste material may include, for example, a resin product that has been used outdoors for a long time and has been deteriorated by heat or ultraviolet rays, so that the melt viscosity and the melt tension are lowered. Further, since the recovered material including the unused product may contain a resin other than the above-mentioned desired resin, the melt viscosity and the melt tension may decrease. As described above, the recovered materials include materials having different melting characteristics because waste materials and unused products used for various purposes are collected. Therefore, if manufactured under certain conditions, the physical properties of the thermoplastic resin composition will be different, and the shape of the resin strand may fluctuate and be cut during the manufacturing process.

Next, the reason why the conditions of the melt kneader and the conditions of the pelletizer must be adjusted will be described. For example, when the shape of the resin strand is normal, the thickness of the resin strand is within the specified value, and the trajectory of the resin strand is also within the specified value. In this case, both the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand are within the specified values.

When the measurement result of the shape of the resin strand does not fall within the specified value, the tension of the resin strand becomes weak. That is, the orbits of the resin and the land are deformed in the direction along the gravity. The causes of the weakening of the resin strand tension are (1) the winding speed of the resin strand by the pelletizer is slow, (2) the melt viscosity of the recovered material is low, and (3) (1) and (2). It includes being both.

When the cause of the weak tension of the resin strand is derived from the above-mentioned (1), the above problem can be solved by increasing the winding speed of the resin strand by the pelletizer. However, when the cause of the weak tension of the resin strand is derived from the above-mentioned (2) or (3), the above problem cannot be solved by adjusting only the winding speed of the resin strand by the pelletizer, and melt kneading is performed. It is also necessary to adjust the conditions of. Therefore, in the present embodiment, the resin is adjusted by adjusting the conditions of the melt kneader and the conditions of the pelletizer based on the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand. Prevents the strands from cutting. When the tension of the resin strand is weak as in the present embodiment and the cause is the above-mentioned (2) or (3), the temperature of the melt-kneading is lowered and the winding speed by the pelletizer is slowed down. The tension of the resin strand can be adjusted so that it falls within the specified value.

When the melt tension of the recovered material is low, the thickness of the resin strand may be thinned overall or partially. Reasons for the thinning of at least a part of the resin strand include (1) a high winding speed by the pelletizer , and (2) a low melt tension of the recovered material. Another cause of the resin strands becoming thin is that the resin strands in the portion become thin due to the inclusion of foreign matter, and the melt tension may partially decrease.

When the cause of the thinning of the resin strand is derived from the above-mentioned (1), the above problem can be solved by slowing the winding speed of the resin strand by the pelletizer. However, when the cause of the thinning of the resin strand is derived from the above-mentioned (2), the above problem cannot be solved even if the winding speed of the resin strand by the pelletizer is adjusted, and it is necessary to adjust the conditions of melt kneading. be. Therefore, in the present embodiment, the resin strands are prevented from being cut by adjusting the conditions of the melt kneader and the conditions of the pelletizer. When the resin strand is thin as in the present embodiment and the cause is (2) described above, the thickness of the resin strand is reduced by lowering the temperature of melt-kneading and slowing down the winding speed by the pelletizer. It can be adjusted to fit within the specified value.

As described above, when at least one of the melt viscosity, the melt tension, and the shape of the resin strand is not included in the specified values, the shape of the resin strand may fluctuate and the resin strand may be cut. Further, in order to determine an appropriate adjustment method for preventing the resin strand from breaking, it may not be sufficient to measure and adjust either the melt viscosity, the melt tension, or the shape of the resin strand. Therefore, as in the present embodiment, when at least one of the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand is not a specified value, the measurement result of the melt viscosity is obtained. , The temperature of the cylinder or the temperature of the die and the winding speed are adjusted so that the measurement result of the melt tension and the measurement result of the shape of the resin strand are within the specified values.

In the sixth step, when at least one of the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand is not a specified value, the measurement result of the melt viscosity and the measurement result of the melt tension are measured. Based on the adjustment table showing the adjustment contents of the melt kneader and the adjustment contents of the pelletizer so that the result and the measurement result of the shape of the resin strand are within the specified values, the temperature of the cylinder or the temperature of the die, The take-up speed may be adjusted.

The adjustment table is prepared for each combination of the melt viscosity range that needs to be adjusted, the melt tension range that needs to be adjusted, the thickness range of the resin strand that needs to be adjusted, and the trajectory of the resin strand that needs to be adjusted. do. The adjustment table may be obtained by simulation or by actual measurement.

Here, a specific example of the adjustment table will be described. For example, first, prioritize whether to adjust the melt viscosity, the melt tension, or the shape of the resin strand. Next, based on the priority, when the melt viscosity, the melt tension, and the shape of the resin strand are not in the default values, which adjustment item is adjusted and how is determined.

Table 1 is a table showing an example of the adjustment table. “As is” in Table 1 means that the adjustment content is not changed.

Then, based on the adjustment table obtained in advance, the temperature of the cylinder or the temperature of the die is adjusted so that the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand are within the specified values. , Adjust the take-up speed.

Hereinafter, a method for producing a thermoplastic resin composition will be described in more detail with reference to the attached drawings. FIG. 1 is a diagram schematically showing a method for producing a thermoplastic resin composition.

As shown in FIG. 1, the recovered material is sorted by wet specific gravity sorting or the like for each type of thermoplastic resin. The sorted recovered material is then washed and then dried.

The dried recovered material is sent to the melt kneader 100. Further, a part of the dried recovered material is sent to the melt viscosity measuring device 200 and the melt tension measuring device 300.

The melt viscosity measuring device 200 measures the melt viscosity of the recovered material. The melt viscosity measuring device 200 transmits an electric signal corresponding to the melt kneading temperature and / or the die temperature based on the measured melt viscosity to the melt kneader 100, and corresponds to the winding speed based on the measured melt viscosity. The generated electric signal is transmitted to the pelletizer 400.

The melt tension measuring device 300 measures the melt tension of the recovered material. The melt tension measuring device 300 transmits an electric signal corresponding to the melt kneading temperature and / or the die temperature based on the measured melt tension to the melt kneader 100, and corresponds to the winding speed based on the measured melt tension. The generated electric signal is transmitted to the pelletizer 400.

The recovered material charged into the charging port 110 is melt-kneaded in the cylinder 120 and discharged from the die 130 as a resin strand.

The resin strand discharged from the die 130 is cooled. In the present embodiment, the resin strand discharged from the die 130 is cooled by traveling under the roller 510 arranged in the water tank 500 filled with water.

Further, the thickness and track (tension) of the resin strand immediately after being discharged are measured by the first measuring device 600 and the second measuring device 700.

FIG. 2 is a schematic view for explaining a process of measuring the shape of the resin strand. As shown in FIG. 2, in the present embodiment, the resin strand discharged from the die 130 of the melt kneader 100 is sent to the downstream side through the lower part of the roller 510 arranged downstream. The first measuring device 600 for measuring the thickness of the resin strand and the second measuring device 700 for measuring the trajectory of the resin strand are arranged side by side in order from the melt kneader 100 side.

As shown in FIG. 2, the thickness of the resin strand is the diameter of the resin strand immediately after being discharged from the die 130. The first measuring device 600 transmits an electric signal corresponding to the melt kneading temperature and / or the die temperature based on the measured thickness of the resin strand to the melt kneader 100, and winds up based on the measured melt tension. An electric signal corresponding to the speed is transmitted to the pelletizer 400.

As shown in FIG. 2, for example, the trajectory of the resin strand draws a tangent line L from the die 130 of the melt kneader 100 to the lower side of the roller 510, and makes the intersection of the tangent line L and the perpendicular line from the second measuring device 700. When the reference point P is set, it is obtained as the distance D between the reference point P and the resin strand in the direction in which the perpendicular line extends. For example, the distance between the reference point P and the resin strand is 0 mm or more and 20 mm or less. That is, when the distance exceeds 20 mm, the conditions of the melt kneader and the conditions of the pelletizer are adjusted in the adjusting step.

The second measuring device 700 arranged on the downstream side where the resin strand is sent from the first measuring device 600 measures the trajectory of the resin strand. The second measuring device 700 transmits an electric signal corresponding to the melt-kneading temperature and / or the die temperature based on the measured resin strand trajectory to the melt-kneader 100, and winds based on the measured resin strand trajectory. An electric signal corresponding to the picking speed is transmitted to the pelletizer 400.

The cooled resin strand is wound up by the pelletizer 400 and cut if necessary to obtain a thermoplastic resin composition.

As is clear from the above description, the recovered material made of thermoplastic resin is melt-kneaded with a melt-kneader, and then the resin strands discharged from the melt-kneader are wound up with a pelletizer to be made of recycled thermoplastic resin. This is a method for producing the composition of the above, from a step of measuring the melt viscosity of the recovered material, a step of measuring the melt tension of the recovered material, a step of melt-kneading the recovered material with a melt-kneader, and a melt-kneader. A step of measuring the shape of the discharged resin strand, a step of obtaining a thermoplastic resin composition by winding the resin strand with a pelletizer while cooling the resin strand, a measurement result of the melt viscosity, a measurement result of the melt tension, and the like. Based on the measurement result of the shape of the resin strand, the step of adjusting the conditions of the melt kneader and the conditions of the pelletizer so as to cancel the fluctuation of the shape of the resin strand due to the variation in the physical properties of the recovered material is included. Therefore, according to the above-mentioned production method, the resin strands discharged from the melt-kneader are not cut, so that the productivity of the thermoplastic resin composition can be increased.

The condition of the melt kneading machine, and the temperature of the cylinder of the melt kneader, and the temperature of the die of the melt kneader, condition of the pelletizer is an winding speed of the resin strands by the pelletizer In the step of adjusting the conditions of the melt kneader and the pelletizer , at least one of the melt viscosity measurement result, the melt tension measurement result, and the resin strand shape measurement result is a specified value. When not, the temperature of the cylinder or the temperature of the die and the temperature of the die so as to keep the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand within the specified values. Adjusting the take-up speed is even more effective from the viewpoint of increasing the productivity of the thermoplastic resin composition.

The condition of the melt kneading machine, and the temperature of the cylinder of the melt kneader, and the temperature of the die of the melt kneader, condition of the pelletizer is an winding speed of the resin strands by the pelletizer In the step of adjusting the conditions of the melt kneader and the conditions of the pelletizer , at least one of the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand is a specified value. When not, the cylinder is based on an adjustment table obtained in advance so that the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand are within the specified values. Adjusting the temperature of the above or the temperature of the die and the winding speed is more effective from the viewpoint of efficiently increasing the productivity of the thermoplastic resin composition.

Further, specifically, the above-mentioned production method is preferably applied to at least one resin selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate and polybutylene terephthalate. It is possible, and it can be preferably applied to the recovered material.

Further, the raw material resin composition further containing one or more additives selected from the group consisting of colorants, flame retardants, lubricants, compatibilizers, antioxidants and ultraviolet absorbers is put into the melt kneader. This is even more effective from the viewpoint of enhancing the functionality or versatility of the product.

[Preparation of materials]
As the material 1, the recovered crushed PC was sorted by wet specific gravity sorting, and the sorted crushed product was washed and dried to prepare a crushed product. As the material 2, the recovered crushed ABS resin was sorted by wet specific gravity sorting, and the sorted crushed product was washed and dried to prepare a crushed product.

[Preparation of twin-screw melt kneader]
As a melt kneader, a twin-screw melt kneader (HYPERKTX 30; Kobe Steel, Ltd.) was prepared.

[Example 1]
Material 1 was dried at 80 ° C. for 4 hours using a vacuum dryer. Next, the mixture was continuously charged at a rate of 10 kg / hour for 10 hours from the inlet of the twin-screw melt-kneader and melt-kneaded. The temperature of the cylinder during melt-kneading was 220 ° C.

On the other hand, the material 1 to be supplied to the inlet was sampled at intervals of 5 minutes, and the melt viscosity and melt tension of the material 1 were measured.

The melt viscosity and melt tension were measured using a capillary rheometer (capillary graph 1D; Toyo Seiki Seisakusho Co., Ltd.).

The shape of the resin strand 1 discharged from the twin-screw melt-kneader was measured with a sensor. As the shape of the resin strand 1, the thickness of the resin strand 1 and the trajectory of the resin strand 1 were measured. The thickness of the resin strand 1 was measured using a laser scan micrometer (LSM-503S; Mitutoyo Co., Ltd.) at a position 10 mm away from the discharge port of the twin-screw melt kneader. The trajectory of the resin strand 1 was measured using a laser displacement sensor (IA-100; KEYENCE CORPORATION) at a position 100 mm away from the discharge port of the twin-screw melt-kneader.

Further, based on the above-mentioned Table 1, adjustment based on the measurement result of the melt viscosity and the measurement result of the melt tension (hereinafter, also referred to as "first adjustment") and adjustment based on the measurement result of the shape of the strand (hereinafter, "" (Also called "second adjustment").

The resin strand 1 whose shape was measured was immersed in water at 30 ° C. and rapidly cooled. Then, the rapidly cooled resin strand 1 was pulverized into pellets by a pelletizer. In this way, a pellet-shaped resin composition 1 was obtained.

[Example 2]
A resin composition 2 was obtained in the same manner as in Example 1 except that a pigment (NUBIANBLACK PC-5857; Orient Chemical Industries Co., Ltd.) was added in an amount of 3% by mass at the time of charging into the twin-screw melt-kneader. rice field.

[Example 3]
The resin composition 3 was obtained in the same manner as in Example 1 except that a flame retardant (SPS-100; Otsuka Chemical Co., Ltd.) was added in an amount of 10% by mass at the time of charging into the twin-screw melt kneader. ..

[Example 4]
A resin composition 4 was obtained in the same manner as in Example 1 except that the material 1 was changed to the material 2.

[Comparative Example 1]
A resin composition 5 was obtained in the same manner as in Example 1 except that the first adjustment and the second adjustment were not performed.

[Comparative Example 2]
A resin composition 6 was obtained in the same manner as in Example 1 except that the first adjustment was not performed.

[Comparative Example 3]
A resin composition 7 was obtained in the same manner as in Example 1 except that the second adjustment was not performed.

[Comparative Example 4]
A resin composition 8 was obtained in the same manner as in Example 1 except that 100 kg of the material 1 was mixed in advance and the first adjustment and the second adjustment were not performed.

Table 2 shows the material of the resin composition and the conditions for melt-kneading.

[evaluation]
A total amount of 100 kg of the resin composition was produced for 10 hours in a row, and the number of times the resin strands were cut and the number of pieces were examined. Then, it was evaluated according to the following evaluation criteria.
⊚: The resin strand was not cut during production.
◯: The number of times that even one resin strand was cut during production was 1 to 2 times, and 2 or more of them were not cut at all.
Δ: The number of times that even one resin strand was cut during production was 3 to 4, and the number of times that two or more were cut was 0 to 1.
X: The number of times that even one resin strand was cut during production was 5 times or more, or the number of times that 2 or more were cut during production was 2 times or more.

Resin Composition No. And the evaluation results are shown in Table 3.

As shown in Table 3, in the resin compositions 1 to 4 subjected to the adjustment step, the thermoplastic resin composition could be continuously produced without cutting the resin strands. On the other hand, in the resin compositions 5 to 8 in which only one of the adjustment based on the measurement result of the melt viscosity and the measurement result of the melt tension or the adjustment based on the observation of the discharge state of the strand was performed, the resin strand was manufactured during the production. Has been disconnected. It is probable that this is because the resin strand was cut because only one of the above adjustments was made.

According to the above-mentioned manufacturing method, it is expected that the effective utilization of the resin material will be expanded, such as the reuse of the recovered material and the effective utilization of the new resin material having the physical characteristics deviating from the intended physical characteristics. Therefore, according to the production method, it is expected that the productivity of the resin composition and the product made from the resin composition is further improved and the environmental load associated with the production of the resin composition and the product is further reduced. NS.

100 Melt kneader 110 Input port 120 Cylinder 130 Die 200 Melt viscosity measuring device 300 Melt tension measuring device 400 Pelletizer 500 Water tank 510 Roller 600 1st measuring device 700 2nd measuring device

Claims (6)

A method for producing a regenerated thermoplastic resin composition by melt-kneading a recovered material made of a thermoplastic resin with a melt-kneader and then winding the resin strands discharged from the melt-kneader with a pelletizer. There,
The step of measuring the melt viscosity of the recovered material and
The step of measuring the melt tension of the recovered material and
The step of melt-kneading the recovered material with the melt-kneader and
A step of measuring the shape of the resin strand including the thickness of the resin strand after being discharged from the melt-kneader and the trajectory of the resin strand after being discharged from the melt-kneader.
A step of obtaining a thermoplastic resin composition by winding the resin strand with the pelletizer while cooling the resin strand.
Based on the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand, the variation in the shape of the resin strand due to the variation in the physical properties of the recovered material is canceled out. Including a step of adjusting the conditions of the melt kneader and the conditions of the pelletizer.
A method for producing a thermoplastic resin composition. The conditions of the melt kneader are the temperature of the cylinder of the melt kneader and the temperature of the die of the melt kneader.
Condition of the pelletizer is the winding speed of the resin strands by the pelletizer,
In the step of adjusting the conditions of the melt kneader and the conditions of the pelletizer , at least one of the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand is not a specified value. At that time, at least one of the temperature of the cylinder and the temperature of the die so as to keep the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand within the specified values. , Adjust the take-up speed,
The method for producing a thermoplastic resin composition according to claim 1. The conditions of the melt kneader are the temperature of the cylinder of the melt kneader and the temperature of the die of the melt kneader.
Condition of the pelletizer is the winding speed of the resin strands by the pelletizer,
In the step of adjusting the conditions of the melt kneader and the conditions of the pelletizer , at least one of the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand is not a specified value. At that time, the adjustment contents of the melt kneader and the adjustment contents of the pelletizer so that the measurement result of the melt viscosity, the measurement result of the melt tension, and the measurement result of the shape of the resin strand are within the specified values. Based on the adjustment table showing the above, at least one of the temperature of the cylinder and the temperature of the die and the winding speed are adjusted.
The method for producing a thermoplastic resin composition according to claim 1. Any of claims 1 to 3, wherein as the thermoplastic resin, at least one resin selected from the group consisting of polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer, polyethylene terephthalate and polybutylene terephthalate is used. The method for producing a thermoplastic resin composition according to item 1. The method for producing a thermoplastic resin composition according to any one of claims 1 to 4, wherein a waste material of a thermoplastic resin is used as the recovery material. The recovered material comprises at least one additive selected from the group consisting of colorants, flame retardants, lubricants, compatibilizers, antioxidants and UV absorbers, according to any one of claims 1-5. The method for producing a thermoplastic resin composition according to the above.

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