JP7024267B2 - Method for manufacturing 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, it has been required to reduce the amount of waste, 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 resin.

Waste materials are generally recovered for each type of thermoplastic resin, and each waste material has unique physical properties according to the original use. Therefore, the waste material generally has the same type of resin but different physical properties. 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 for adjusting the melt-kneading time is known (see, for example, Patent Document 1). In this technique, a time is set for each type of waste material and melt-kneaded to obtain a raw material for a thermoplastic resin having a desired melt viscosity.

Japanese Unexamined Patent Publication No. 2004-204210

When melt-kneading waste materials with no variation in physical properties using an extrusion-kneader, the above-mentioned technique is adopted, the melt-kneading time is set, and the barrel length is selected once, and it is continuously desired. It can be reused as a raw material for new products made of thermoplastic resin having a melt viscosity of.

On the other hand, when the waste material having physical properties as described above is melt-kneaded, it is necessary to set the melt-kneading time and change the barrel length according to the physical properties. As described above, in order to change the length of the barrel, it is necessary to stop the melt-kneading, which may significantly reduce the productivity of the raw material.

The present invention provides a method for continuously producing a thermoplastic resin composition capable of sufficiently reducing the variation in the physical properties of a product due to the variation in the physical properties of the raw material by using a raw material made of a thermoplastic resin having variations in the physical properties. The challenge is to do.

As one aspect for solving the above-mentioned problems, the present invention feeds a recovered material made of a thermoplastic resin from at least one of a plurality of charging ports at different distances from the discharging port of the melt-kneader and regenerates the material. A method for producing a composition made of a thermoplastic resin, which comprises a step of measuring the melt viscosity of the recovered material, a step of measuring the metal content of the recovered material, and the measured melt viscosity and the metal. A step of selecting the charging port for charging the recovered material based on the rate of decrease in the melting viscosity at the time of melt-kneading obtained from the content and the desired melting viscosity of the recycled product, and the step of selecting the charging port to the selected charging port. It includes a step of adding the recovered material and melting and kneading it.

According to the present invention, variations in products made of thermoplastic resin are sufficiently reduced.

FIG. 1 is a schematic view of an extruder / kneader showing a positional relationship between an input port and a discharge port. FIG. 2 is a schematic graph showing the relationship between the positional relationship between the discharge port and the input port and the melt viscosity. FIG. 3A is a schematic graph for explaining a selection process when the recovered material contains metal, and FIG. 3B is a schematic for explaining a method for correcting the melt viscosity when the recovered material contains metal. It is a figure. FIG. 4 is a diagram schematically showing the relationship between the melt viscosity, the metal content, and the position of the input port to be selected. FIG. 5 is a diagram schematically showing a method for producing a thermoplastic resin composition.

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 melt viscosity measuring step, a metal content measuring step, a selection step, and a melt kneading step.

The melt viscosity measuring 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 or crushed products thereof that are recovered before they are put on the market. including. When used as a thermoplastic resin, waste materials and unused products are usually classified as crushed products according to the type of resin, or used as a mixture of 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 colorants for resins 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 higher fatty acid metal salts 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. Further, 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.

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 charging port of the kneading extruder, 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 charging port. The measurement of the melt viscosity may be completed before the recovered material is charged into the charging port.

Further, as an index of the melt viscosity, a 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. 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 metal content measuring step is a step of measuring the metal content of the recovered material.

The measurement of the metal content 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 kneading extruder, the metal content may be measured at arbitrary intervals.

More specifically, a part of the recovered material may be sampled and the metal content contained in the recovered material may be measured while the recovered material is being conveyed to the charging port. The measurement time of the metal content may be terminated after sampling and before the recovered material is charged into the charging port.

Further, the metal content may be determined as the total amount of the metal adhering to the surface of the thermoplastic resin and the amount of metal mixed in the inside of the thermoplastic resin.

Regarding the metal content adhering to the surface of the thermoplastic resin, first, the surface of the thermoplastic resin is washed with pure water, and the metal salt or the like adhering to the surface of the thermoplastic resin is dissolved in pure water. Then, the content of the metal salt contained in the solution is calculated by measuring the electric conductivity of the solution in which the metal salt or the like is dissolved. Next, the metal content adhering to the surface of the thermoplastic resin is measured from the content of the metal salt.

The amount of metal mixed in the thermoplastic resin is determined by fluorescent X-ray analysis to determine the type of metal mixed in the thermoplastic resin and to quantify each metal. Finally, the metal content adhering to the surface of the thermoplastic resin and the metal content mixed in the inside of the thermoplastic resin may be totaled to obtain the metal content of the recovered material.

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

In the selection step, the recovered material is charged based on the rate of decrease in melt viscosity during melt kneading (rate of increase in MFR value) obtained from the measured melt viscosity and metal content, and the desired melt viscosity of the recycled product. Select (control) the mouth.

First, prior to the measurement step, data showing the relationship between the melt viscosity, the metal content, and the position of the charging port is prepared. The data showing the relationship between the melt viscosity, the metal content, and the position of the charging port is for each thermoplastic resin for each melt viscosity of the thermoplastic resin composition of the recycled product, and the type of metal contained. And prepare for each metal content. Specifically, in the case of a recovered material that does not contain metal, data is prepared for each thermoplastic resin. In addition, for each thermoplastic resin, data is prepared for each melt viscosity of the thermoplastic resin composition of the recycled product.

Further, in the case of a recovered material containing a metal, data is prepared for each type of metal contained and the combination of metals. Also, prepare data for each amount of metal contained. As described above, by preparing the data in advance, it is possible to know to which input port the recovered material should be charged to obtain a thermoplastic resin composition having a desired melt viscosity.

The rate of decrease in the melt viscosity of the recovered material containing no metal (rate of increase in the MFR value) is the same as the rate of decrease in the melt viscosity of the unused product (rate of increase in the MFR value). On the other hand, the rate of decrease in the melt viscosity of the recovered material containing the metal (rate of increase in the MFR value) is larger than the rate of decrease in the melt viscosity of the unused product (rate of increase in the MFR value). This is because the metal accelerates the deterioration of the thermoplastic resin.

First, a case where the recovered material does not contain metal will be described. FIG. 1 is a schematic view of an extruder / kneader showing a positional relationship between an input port and a discharge port. As shown in FIG. 1, the inlets are arranged in the order of the inlet A, the inlet B, the inlet C, and the inlet D as the distance from the discharge port increases. FIG. 2 is a schematic graph showing the relationship between the positional relationship between the discharge port and the input port and the melt viscosity. The horizontal axis of FIG. 2 shows the positional relationship between the input port and the discharge port. That is, the horizontal axis indicates the time for melt-kneading. The vertical axis of FIG. 2 shows the melt viscosity.

As described above, the rate of decrease in the melt viscosity of the recovered material is the same as the rate of decrease in the melt viscosity of the unused product. In this case, one data satisfying the type of thermoplastic resin contained in the recovered material (for example, PC) and the melt viscosity of the recycled product is selected. Then, the charging port to be charged is selected from the measured melt viscosity of the recovered material.

Specifically, for example, the melt viscosity of the recovered material is the melt viscosity 2 shown in FIG. 2, the melt viscosity of the unused product is the melt viscosity 3 shown in FIG. 2, and the melt viscosity of the recycled product is shown in FIG. If the melt viscosity is 1, the charging port A is selected as the charging port. In this way, when the melt viscosity (MFR value) of the recovered material is lower than the melt viscosity of the unused product (higher than the MFR value), the melt kneading is performed by selecting the feed port near the discharge port as the feed port. It is possible to obtain a recycled thermoplastic resin composition having a desired melt viscosity by shortening the time required.

On the other hand, when the melt viscosity of the recovered material is the melt viscosity 4 shown in FIG. 2, the charging port C is selected as the charging port. As described above, when the melt viscosity (MFR value) of the recovered material is higher than the melt viscosity of the unused product (lower than the MFR value), the time for melt-kneading is performed by selecting a feed port farther away as the feed port. It is possible to obtain a recycled thermoplastic resin composition having a desired melt viscosity.

Next, a case where a metal is detected in the recovered material in the step of measuring the amount of contained metal, that is, a case where the recovered material contains a metal will be described. FIG. 3A is a schematic graph for explaining a selection process when the recovered material contains a metal. The horizontal axis of FIG. 3A shows the positional relationship between the input port and the discharge port. That is, the horizontal axis indicates the time for melt-kneading. The vertical axis of FIG. 3A shows the melt viscosity. L1 in FIG. 3A shows the variation in the melt viscosity of the recovered material containing no metal, L2 in FIG. 3A shows the variation in the melt viscosity of the recovered material containing metal, and L3 in FIG. 3A. Shows the fluctuation of the melt viscosity of the recovered material containing metal when the melt viscosity of the recycled product is matched with the melt viscosity of the recovered material containing no metal in L2.

The rate of decrease in the melt viscosity of the recovered material containing the metal (rate of increase in the MFR value) is larger than the rate of decrease in the melt viscosity of the recovered material containing no metal (rate of increase in the MFR value). This is because, as described above, the metal accelerates the deterioration of the thermoplastic resin. In this case, one data satisfying the type of thermoplastic resin contained in the recovered material, the type of metal contained, the concentration of each metal, and the melt viscosity of the recycled product is selected. Then, the charging port to be charged is selected from the measured melt viscosity of the recovered material.

More specifically, for example, when the melt viscosity of the recovered material is 4, the melt viscosity shown in FIG. 2, the rate of decrease in the melt viscosity of the recovered material (L2) containing a metal is such that the metal is not contained. It is larger than the rate of decrease in the melt viscosity of the recovered material (L1). As described above, the recovery material (L2) containing metal has a higher rate of deterioration than the recovery material (L1) containing no metal. Therefore, when the recovered material containing metal is melt-kneaded as in the case of the recovered material containing no metal, the thermoplastic resin of the recycled product discharged from the discharge port becomes lower than the desired melt viscosity. Therefore, data (L3) is selected in which the melt viscosity of the recycled product when the recovered material containing metal is melt-kneaded is matched with the melt viscosity of the recycled product of the thermoplastic resin containing no metal. Finally, based on the data, the input port to be input is selected. That is, in this example, the input port A is selected as the input port.

Next, a method for correcting the melt viscosity when a metal is detected in the recovered material, that is, when the recovered material contains a metal will be described. FIG. 3B is a schematic graph for explaining a method of correcting the melt viscosity when the recovered material contains a metal. The horizontal axis of FIG. 3B shows the positional relationship between the input port and the discharge port. That is, the horizontal axis indicates the time for melt-kneading. The vertical axis of FIG. 3B shows the melt viscosity. L1 of FIG. 3B shows the fluctuation of the melt viscosity of the recovered material when the metal and the metal inactivating agent are contained, and L2 of FIG. 3B contains the metal and does not contain the metal inactivating agent. The variation of the melt viscosity of the recovered material in the case is shown, and L3 of FIG. 3B shows the variation of the melt viscosity of the recovered material when the melt viscosity of the recovered material is corrected in L2.

As described above, the rate of decrease in the melt viscosity of the recovered material containing metal is larger than the rate of decrease in the melt viscosity of the recovered material containing no metal. In this case, it is effective to include the metal inactivating agent in the recovered material to suppress the acceleration of deterioration of the metal with respect to the thermoplastic resin. However, the melt viscosity (MFR value) of the recovered material containing metal tends to be measured lower (higher than the MFR value) than the melt viscosity of the unused recovered material containing no metal. Therefore, when metal is contained in the recovered material, it is necessary to correct the measured melt viscosity (MFR value). The details of the step of containing the metal inactivating agent will be described later.

As shown in FIG. 3B, it is assumed that the melt viscosity of the recovered material containing no metal is 5 and the melt viscosity of the recovered material containing metal is 4. Further, it is assumed that the melt viscosity of the recycled product is 1.

As shown in FIG. 3B, the rate of decrease in melt viscosity (L2) of the recovered material containing metal is larger than the rate of decrease in melt viscosity (L1) of the recovered material containing no metal. Therefore, a metal inactivating agent is added to the recovered material containing metal to correct the rate of decrease in the recovered material containing metal to the rate of decrease in melt viscosity (L1) of the recovered material containing no metal. .. However, the actual melt viscosity of the recovered material is not the melt viscosity 4 but the melt viscosity 5.

Therefore, in the present embodiment, in consideration of the fact that the melt viscosity of the recovered material containing a metal is measured to be low and the melt viscosity of the thermoplastic resin composition of the recycled product is high, the melt viscosity is increased in the selection step. The melt viscosity is corrected (L3).

Specifically, the reduction value of the melt viscosity is obtained in advance for each combination of the type of metal contained in the recovered material and the content of each metal. Then, by adding the reduced value to the melt viscosity of the recovered material measured in the measuring step so as to offset the reduced value, the influence of the metal and the metal inactivating agent is suppressed. Then, based on the corrected melt viscosity, the data is selected and the input port is selected. In the above example, the input port D is selected as the input port.

FIG. 4 schematically shows the relationship between the melt viscosity of the recovered material, the metal content, and the position of the input port to be selected when the metal inactivating agent is added according to the metal content contained in the recovered material. It is a figure which shows.

As shown in FIG. 4, in the selection step, the recovery material contains metal, and the higher the metal content, the farther the inlet is selected from the discharge port (than the one without metal). When the recovered material contains a metal, the recovered material is measured to have a lower melt viscosity than when no metal is contained in the melt viscosity measuring step. However, when the metal inactivating agent is added in the kneading step, the melt viscosity at the time of charging the recovered material into the melt kneader is higher than that at the time of measuring the melt viscosity. Select a mouth. Further, when the melt viscosity is high, the difference between the melt viscosity of the recovered material and the melt viscosity of the thermoplastic resin composition to be produced is large. Therefore, in the selection step, since it is necessary to lengthen the melt-kneading time, a charging port far from the discharge port is selected.

As shown in FIG. 4, in the selection step, the recovery material contains metal, and the higher the metal content, the farther the inlet is selected from the discharge port (than the one without metal). When the recovered material contains a metal, the recovered material is measured to have a lower melt viscosity than when no metal is contained in the melt viscosity measuring step. However, when the metal inactivating agent is added in the kneading step, the melt viscosity at the time of charging the recovered material into the melt kneader is higher than that at the time of measuring the melt viscosity. Select a mouth. Further, when the melt viscosity is high, the difference between the melt viscosity of the recovered material and the melt viscosity of the thermoplastic resin composition to be produced is large. Therefore, in the selection step, since it is necessary to lengthen the melt-kneading time, a charging port far from the discharge port is selected.

Since the melt viscosity of the discharged thermoplastic resin composition may be controlled so as to be within a certain range, if there is no data that completely matches the melt viscosity and the metal content in the measurement step, , Use the closest data.

In the melt-kneading step, the recovered material is charged into the selected charging port and melt-kneaded. As described above, since the measurement steps are performed at predetermined intervals, the input port is also selected at predetermined intervals. As described above, in the melt-kneading, the recovered materials can be continuously charged and the thermoplastic resin composition can be continuously obtained by switching the charging ports at predetermined intervals.

The cylinder temperature at the time of 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, for example, in the case of a twin-screw extrusion kneader as shown in FIG. 1, the time from charging from the charging port D to discharging from the discharging port is, for example, about 5 minutes, and charging is performed from the charging port C. The time from the discharge port to the discharge is, for example, about 4 minutes and 30 seconds, and the time from the input port B to the discharge from the discharge port is, for example, about 4 minutes. The time from the discharge port to the discharge is, for example, about 3 minutes and 30 seconds.

In this way, a thermoplastic resin composition exhibiting a desired melt viscosity (MFR value) can be continuously obtained.

Further, the method for producing the thermoplastic resin composition according to the present embodiment includes, as an arbitrary step, a step of adding a metal inactivating agent, a step of adding an additive, a cooling step, and a crushing step. , And a molding step may be further included.

In the step of adding the metal inactivating agent, the metal inactivating agent is added in an amount corresponding to the metal content measured in the measuring step. The inlet for charging the metal inactivating agent can be appropriately selected.
The recovered material and the metal inactivating agent are preferably charged into one inlet selected in the selection step from the viewpoint of efficiently acting the metal inactivating agent.

Examples of metal inactivating agents include oxalic acid derivatives, salicylic acid derivatives, hydrazide derivatives, triazole derivatives, and imidazole derivatives.

Examples of oxalic acid derivatives include oxalo-bis-1,2-hydroxybenzylidene hydrazide (Eastman inhibitor OABH; Eastman Kodak), 2,2'-oxamidbis (ethyl 3- (3,5-tert-butyl-4). -Hydroxyphenyl) propionate) (Naugard XL-1; Shiraishi Calcium Co., Ltd., "Naugard" is a registered trademark of the company).

Examples of salicylic acid derivatives include 3- (N-salicyloyl) amino-1,2,4-triazole (ADEKA-1; ADEKA Corporation, "ADEKASTAB" is a registered trademark of the same company), decamethylene dicarboxylic acid disalicylo. Includes ilhydrazide (ADEKA STAB CDA-6; ADEKA Corporation), salicylidene salicyloylhydrazine (Chel-180; BASF).

Examples of hydrazide derivatives include N, N'-bis ((3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl)) propionohydrazide (CDA-10; ADEKA Corporation, Qunox; Mitsui Toatsu Fine Co., Ltd., "Quant" is a registered trademark of the company).

Examples of triazole derivatives include benzotriazole, 3-amino-1,2,4-triazole, 2-mercaptobenzotriazole, 2,5-dimercaptobenzotriazole, 4-alkylbenzotriazole, 5-alkylbenzotriazole, 4 , 5,6,7-Tetrahydrobenzotriazole, 5,5'-methylenebisbenzotriazole, 1- [di (2-ethylhexyl) aminomethyl] -1,2,4-triazole, 1- (1-butoxyethyl) -1,2,4-triazole and acylated 3-amino-1,2,4-triazole are included.

Examples of imidazole derivatives include 4,4'-methylenebis (2-undecylic-5-methylimidazole, bis [(N-methyl) imidazol-2-yl] carbinol octyl ether.

The metal inactivating agent is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, from the viewpoint of inactivating the metal contained in the recovered material. Further, the metal inactivating agent is preferably 1% by mass or less from the viewpoint of saturating the effect of inactivating the metal contained in the recovered material.

In the step of adding the additive, the additive is added in an amount corresponding to the metal content measured in the measuring step. The input port for charging the additive can be appropriately selected. From the viewpoint of efficient action of the additive, the recovered material and the additive are preferably charged into one charging port selected in the selection step.

The cooling step is a step of cooling the thermoplastic resin composition discharged from the discharge port. The method for cooling the thermoplastic resin composition may be air cooling, air cooling, or water cooling. The method for cooling the thermoplastic resin composition is preferably water cooling from the viewpoint of cooling efficiency. Further, the temperature of the thermoplastic resin composition after the cooling temperature can be appropriately set. For example, the cooling temperature of the thermoplastic resin composition is 30 ° C.

The pulverization step is a step of pulverizing the thermoplastic resin composition solidified by the cooling step. The pulverized thermoplastic resin composition can be used as a raw material for a resin molded product. Therefore, the thermoplastic resin composition is pulverized in a pulverization step so as to be used as a raw material for injection molding, for example, to obtain pellets having an appropriate size.

The molding step is a step of press-fitting the thermoplastic resin composition into a molding die. As described above, the thermoplastic resin composition may be molded as it is after being discharged from the discharge port.

As shown in FIG. 1, the melt-kneader may be a melt-kneader in which a plurality of inlets and one discharge port are connected by one barrel. Further, one inlet and one discharge port are connected by one barrel, and a plurality of melt kneaders having different barrel lengths may be used. In this case, in the selection step, which melt kneader input port is selected. The length of the barrel is L.

Hereinafter, a method for producing a thermoplastic resin composition will be described in more detail with reference to the attached drawings. FIG. 5 is a diagram schematically showing a method for producing a thermoplastic resin composition. In this embodiment, a case where the MFR value is measured as the melt viscosity will be described.

As shown in FIG. 5, 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 mixer 100. Further, a part of the dried recovered material is sent to the metal content measuring device 200 and the MFR measuring device 300.

The metal content measuring device 200 measures the metal content contained in the recovered material. The metal content measuring device 200 determines whether or not to add a metal inactivating agent based on the measured metal content, and if a metal inactivating agent is required, the metal inactivating agent. An electric signal corresponding to the addition amount of the metal inactivating agent is transmitted to the metal inactivating agent addition device 400.

The metal deactivating agent addition device 400 adds the metal deactivating agent to the mixer 100 based on the received electric signal. Further, if necessary, the additive addition device 500 adds various additives to the mixer 100. Further, the metal content measuring device 200 transmits an electric signal corresponding to the amount of the metal inactivating agent added to the inlet switching device 600. On the other hand, when the metal inactivating agent is not required, an electric signal corresponding to the fact that the metal inactivating agent is not required is transmitted to the input port switching machine 600.

Further, the MFR measuring device 300 measures the MFR value of the recovered material. The MFR measuring device 300 transmits an electric signal corresponding to the MFR value to the input port switching device 600.

The input port switching machine 600 considers the influence of the melt viscosity and the metal content on the recovered material at the time of melt kneading based on the electric signal received from the metal content measuring device 200 and the electric signal received from the MFR measuring device 300. Select the data showing the relationship between the melt viscosity and the multiple inlets. Then, the input port switching machine 600 selects the optimum input port based on the selected data.

The input port switching machine 600 mixes the metal inactivating agent and the additive with the recovered material at the timing when the recovered material whose melt viscosity and metal content are measured is sent to the mixer. Then, the charging port switching machine 600 switches the charging port at the timing when the recovered material whose melt viscosity and metal content are measured is sent to the charging port.

The recovered material charged into the selected charging port is melt-kneaded by a melt-kneader and discharged as a thermoplastic resin composition from the discharge port.

As is clear from the above description, the recovered material made of thermoplastic resin is charged from at least one of a plurality of charging ports at different distances from the discharge port of the melt-kneader, and the material is made of recycled thermoplastic resin. A method for producing a composition, which is a step of measuring the melt viscosity of the recovered material, a step of measuring the metal content of the recovered material, and a melt kneading method obtained from the measured melt viscosity and the metal content. Based on the rate of decrease in the melt viscosity of the recycled product and the desired melt viscosity of the recycled product, a step of selecting the charging port for charging the recovered material and charging the recovered material into the selected charging port to melt the material. Including the step of kneading. Therefore, according to the above manufacturing method, it is possible to sufficiently reduce the variation in the physical properties of the recovered material to the extent that the recovered material can be reused as the material of the thermoplastic resin product.

Further, it is more effective from the viewpoint of suppressing deterioration of the thermoplastic resin due to the metal to further include the step of adding the metal inactivating agent in an amount corresponding to the metal content to the recovered material.

Further, charging the recovered material and the metal inactivating agent into one selected inlet is even more effective from the viewpoint of effectively acting the metal inactivating agent.

Further, the above-mentioned production method can be preferably applied to at least one resin selected from the group consisting of PE, PP, PS, ABS resin, PC, PET and PBT, and the recovered material. It is possible to preferably apply to.

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 thermoplastic resin]
As the thermoplastic resin 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 thermoplastic resin 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 extrusion kneader]
A twin-screw extrusion kneader (Kobe Steel, Ltd.) was prepared as a melt kneader. The twin-screw extruder has a barrel and four inlets connected to the barrel. The distance between the centers of the farthest inlets was 30% of the length of the barrel.

[Example 1]
The thermoplastic resin 1 was dried at 80 ° C. for 4 hours using a vacuum dryer. Then, from the charging port of the twin-screw extrusion kneader (HYPERKTX 30; Kobe Steel, Ltd.), the mixture was continuously charged at a rate of 10 kg / hour for 10 hours and melt-kneaded. The cylinder temperature during melt kneading was 270 ° C.

On the other hand, the thermoplastic resin 1 to be supplied to the inlet was sampled at 5-minute intervals, and the MFR value and the metal content of the thermoplastic resin 1 were measured.

The measurement of MFR was performed according to JIS-K7210. More specifically, the MFR value was measured using a melt indexer G-01 (Toyo Seiki Seisakusho Co., Ltd.) at a measurement temperature of 300 ° C., a load of 1.2 kg, or a load of 1.0 kg. The measurement time of the MFR value was 6 minutes. In this example, since the measurement time of the MFR value is longer than the sampling interval of the thermoplastic resin 1, a plurality of melt indexers are used.

Regarding the metal content adhering to the surface of the thermoplastic resin, first, 10 g of the thermoplastic resin is immersed in 100 g of pure water and stirred for 3 minutes, and the metal salt or the like adhering to the surface of the thermoplastic resin is added to the pure water. Dissolved. Then, the content of the metal salt contained in the solution was calculated by measuring the electric conductivity of the solution in which the metal salt or the like was dissolved with an electric conductivity meter (AS710; AS ONE Corporation). Then, the metal content adhering to the surface of the thermoplastic resin was measured from the content of the metal salt. The measurement time of the metal content adhering to the surface of the thermoplastic resin was 4 minutes. The amount of metal mixed in the thermoplastic resin was determined by fluorescent X-ray analysis to determine the type of metal mixed in the thermoplastic resin and to quantify each metal.

The inlet was then controlled based on the MFR value and metal content of the sampled thermoplastic resin 1. The setting of the charging port was controlled based on the data selected in advance according to the melt viscosity and the metal content.

The melt-kneaded thermoplastic resin 1 was extruded from a discharge port, then immersed in water at 30 ° C. and rapidly cooled. Then, the rapidly cooled resin composition 1 was pulverized into pellets by a pelletizer. In this way, the pellet-shaped resin composition 1 was obtained. The time required for the thermoplastic resin 1 to reach the discharge port from the input port of the twin-screw extruder was about 5 minutes.

[Example 2]
The resin composition is the same as in Example 1 except that the metal inactivating agent is added, the metal inactivating agent is charged from a charging port different from that of the thermoplastic resin, and the melt viscosity is corrected by the MFR value. I got 2.

[Example 3]
The resin composition 3 was obtained in the same manner as in Example 2 except that the metal inactivating agent was charged from the same inlet as the resin composition.

[Example 4]
A resin composition 4 was obtained in the same manner as in Example 2 except that the 5% by mass thermoplastic resin 1 was changed to a 5% by mass pigment (NUBIANBLACK PC-5857; Orient Chemical Industries Co., Ltd.).

[Example 5]
A resin composition 5 was obtained in the same manner as in Example 3 except that the 10% by mass thermoplastic resin 1 was changed to a 10% by mass flame retardant (SPS-100; Otsuka Chemical Co., Ltd.).

[Example 6]
A resin composition 6 was obtained in the same manner as in Example 3 except that the thermoplastic resin 1 was changed to the thermoplastic resin 2.

[Example 7]
A resin composition 7 was obtained in the same manner as in Example 3 except that the distance between the centers of the farthest input ports was set to a length of 10% of the length of the barrel.

[Example 8]
The resin composition 8 was obtained in the same manner as in Example 8 except that the charging port was not controlled.

[Example 9]
A resin composition 9 was obtained in the same manner as in Example 8 except that the charging port was not controlled and the melt viscosity was not corrected by the MFR value.

[Example 10]
Except that the 50% by mass thermoplastic resin 1 was changed to 50% by mass virgin PC, the charging port was not controlled, the melt viscosity was not corrected by the MFR value, and no metal inactivating agent was added. The resin composition 10 was obtained in the same manner as in Example 1.

[Example 11]
The resin composition 11 was obtained in the same manner as in Example 1 except that the charging port was not controlled and the metal inactivating agent was not added.

Table 1 shows the material of the resin composition and the conditions for melt-kneading.

[evaluation]
(1) MFR measurement The MFR values of the obtained pellet-shaped resin compositions 1 to 11 were measured in the same manner as the MFR values of the sampled recovered materials in accordance with "JIS K7210". Then, the variation X _MFR (%) of each MFR value of the resin compositions 1 to 11 was obtained from the following formula based on the following formula, and evaluated according to the following evaluation criteria.
(Equation) X _MFR (%) = (M _Rmax -M _Rmin ) / {( _MOmax + _MOmin ) / 2} × 100

In the above formula, " _MRmax " represents the maximum value (g / 10 minutes) of the MFR of the resin composition, " _MRmin " represents the minimum value (g / 10 minutes) of the MFR of the resin composition, and "M". " _Omax " represents the maximum value (g / 10 minutes) of the MFR of the sampled recovered material, and " _MOmin " represents the minimum value (g / 10 minutes) of the MFR of the sampled recovered material.

(Evaluation criteria)
⊚: X _MFR is less than 3.0% ○: X _MFR is 3.0% or more and less than 7.5% Δ: X _MFR is 7.5% or more and less than 10.0% ×: X _MFR is 10.0% or more If it is "◎", "○" and "△", it can be judged that there is no practical problem.

(2) Tensile test After each of the pellet-shaped resin compositions 1 to 11 was dried at 80 ° C. for 4 hours, the cylinder set temperature was set to 230 ° C. by an injection molding machine (J55ELII manufactured by Japan Steel Works, Ltd.). Molding was performed at a mold temperature of 50 ° C. to obtain a (dumbbell-shaped) test piece having a predetermined shape specified in "JIS K7161".

A tensile test was carried out in accordance with "JIS K7161" using each of the test pieces of the resin compositions 1 to 11. Then, the variation degree _XTS (%) of the tensile strength of each of the resin compositions 1 to 11 was obtained from the following formula and evaluated according to the following evaluation criteria.
(Equation) X _TS (%) = ( _TRmax - _TRmin ) / {( _TOmax + _TOmin ) / 2} × 100

In the above formula, " _TRmax " represents the maximum tensile strength (MPa) of the resin composition, " _TRmin " represents the minimum tensile strength (MPa) of the resin composition, and " _TOmax " represents sampling. The maximum tensile strength (MPa) of the recovered material is represented, and " _TOmin " represents the minimum tensile strength (MPa) of the sampled waste material.

(Evaluation criteria)
⊚: X _TS is less than 5.0% ○: X _TS is 5.0% or more and less than 10.0% Δ: X _TS is 10.0% or more and less than 15.0% ×: X _TS is 15.0% or more If it is "◎", "○" and "△", it can be judged that there is no practical problem.

(3) Impact test An impact test was carried out in accordance with "JIS K7110" using each of the test pieces of the resin compositions 1 to 11. Then, the impact strength variation degree _XIS (%) of each of the resin compositions 1 to 11 was obtained from the following formula and evaluated according to the following evaluation criteria.
(Equation) X _IS (%) = (I _Rmax -I _Rmin ) / {(I _Omax + I _Omin ) / 2} × 100

In the above formula, " _IRmax " represents the maximum value of the impact strength of the resin composition (kJ / m ² ), and " _IRmin " represents the minimum value of the impact strength of the resin composition (kJ / m ² ). "I _Omax " represents the maximum value of the impact strength of the recovered material (kJ / m ² ), and " _IOmin " represents the minimum value of the impact strength of the waste material (kJ / m ² ).

(Evaluation criteria)
⊚: _XIS is less than 5.0% ○: _XIS is 5.0% or more and less than 10.0% Δ: _XIS is 10.0% or more and less than 15.0% ×: _XTS is 15.0% or more If it is "◎", "○" and "△", it can be judged that there is no practical problem.

The results are shown in Table 2.

As shown in Table 2, in the resin compositions 1 to 11 in which the charging port was controlled based on the measured melt viscosity and metal content of the recovered material and melt-kneaded, the melt viscosity, tensile test and impact were performed. Both results of the test were excellent. It is considered that this is because the charging port was controlled based on the measured melt viscosity and metal content of the recovered material, so that the melt kneading could be performed appropriately. In particular, the resin compositions 1 to 3 and 6 to which no additive was added had less variation in the results of the melt viscosity, the tensile test and the impact test. It is probable that this was because the data and the behavior during melt-kneading of the thermoplastic resin were close to each other because no additive was contained.

On the other hand, the resin composition 8 to which the metal deactivating agent was added and the input port was not controlled, and the resin composition 9 to which the metal inactivating agent was added and the input port was controlled but the viscosity was not corrected. The MFR value and the results of the impact resistance test varied. It is probable that these were due to the high MFR value due to improper control of the inlet. Further, in the resin composition 10 which did not contain the metal inactivating agent and did not control the charging port, only the results of the impact test varied. It is considered that this is because half of the resin composition was virgin PC. Further, in the resin composition 11 which did not contain the metal inactivating agent and did not control the charging port, the results of the melt viscosity, the tensile test and the impact test were all different.

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 will be further improved and the environmental load associated with the production of the resin composition and the product will be further reduced. To.

100 Mixer 200 Metal content measuring device 300 MFR measuring device 400 Metal deactivating agent addition device 500 Additive addition device 600 Input port switching machine

Claims (6)

A method in which a recovered material made of a thermoplastic resin is charged from at least one of a plurality of charging ports located at different distances from the discharge port of a melt-kneader to produce a recycled composition made of a thermoplastic resin. ,
A step of preparing data showing the relationship between the melt viscosity of the recovered material, the metal content of the recovered material, and the position of the charging port.
The step of producing the composition made of the regenerated thermoplastic resin, and
Have,
The step of producing the composition made of the regenerated thermoplastic resin is
The step of measuring the melt viscosity of the recovered material and
The step of measuring the metal content of the recovered material and
Based on the measured melt viscosity and the rate of decrease in melt viscosity during melt kneading obtained from the metal content, the desired melt viscosity of the recycled product, and the data, the input port for charging the recovered material is selected. And the process to do
The step of charging the recovered material into the selected charging port and melting and kneading the material, and
Including
The specifications of the melt-kneader and the form of the recovered material in the data are the same as the specifications of the melt-kneader and the form of the recovered material in the step of producing the composition made of the regenerated thermoplastic resin.
A method for producing a thermoplastic resin composition. The step of producing the composition made of the regenerated thermoplastic resin according to claim 1, further comprising a step of adding a metal inactivating agent in an amount corresponding to the metal content to the recovered material. A method for producing a thermoplastic resin composition. The method for producing a thermoplastic resin composition according to claim 2, wherein the recovered material and the metal deactivating agent are charged into one selected inlet. 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 any one of claims 1 to 5, comprising at least one additive selected from the group consisting of colorants, flame retardants, lubricants, compatibilizers, antioxidants and UV absorbers. The method for producing a thermoplastic resin composition according to the above.

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